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Opus v. 2.00 -------------- Spreadsheet and Charting program for the Atari ST by Doug Harrison >>> Introduction Opus is a GEM spreadsheet and charting program, which I think you'll find powerful, fast, and easy to use. In order to keep this documentation to a reasonable length, I'll focus primarily on description of features, rather than provide a full tutorial (which probably isn't needed). Some of you may be familiar with the original version of Opus, which appeared in the Sept. 1988 ST-Log. If you fall into this category, great! You can skip over the majority of the spreadsheet description, but please be sure to read the section on charts and the files INSTALL.DOC and CHANGES.DOC. >>> Shareware Opus versions 2.00 and above are shareware. Opus version 2.00 is the result of about 8-9 months of additional work and includes many new features above and beyond the original; the charting facility is completely new, and the spreadsheet is much faster in all operations (for a description of most of the changes and additions, please see the file CHANGES.DOC). I plan on supporting Opus with at least one or two upgrades, and I will be available to answer questions through the mail and on Compuserve and GEnie. If you find Opus useful and wish to support my efforts, you can send a check for $15 (or whatever you feel the program is worth!) to: Doug Harrison P.O. Box 66236 Baton Rouge, LA 70806-6236 For quick response to questions, my Compuserve ID is 72277,2315 and my GEnie mailbox address is D.S.HARRISON. There also is (or soon will be) an Opus topic in Category 2 of the GEnie message base. >>> Distribution Policy You may freely distribute Opus (and please do), as long as all files and notices are included. It may be included as part of "shareware disks" provided by various groups, as long as no fee beyond media costs is charged. >>> Running Opus IF YOU READ NOTHING ELSE, PLEASE, PLEASE READ INSTALL.DOC!!!! Read it NOW, before you try to run Opus! It really and truly DOES contain ESSENTIAL information, OK?! (forgive my tone, I'm just speaking as I need to be spoken to...) Here's a list of the files Opus tries to load when it's executed, in order: 1. OPUSMONO.RSC or OPUSCOLR.RSC (depending on monitor in use) 2. PRINTER.INF (printer control codes) 3. OPUS.CNF (configuration file, explained later) 4. screen fonts, provided GDOS is present 5. OPUS.WID (printer font widths file) Opus doesn't need to access the disk it was loaded from once it has booted. However, when printing charts on a floppy-based system, the disk containing the GDOS files must be present in the boot drive. Please see the section "Printing Charts" for details. March 12, 1989 p. 2 Opus v. 2.00 /////////////////////////////////////////////// ///// Worksheets ///// /////////////////////////////////////////////// Now that you've got Opus up and running, you should have a blank worksheet on your screen. Let's first take a look at "The Panel", the area directly underneath the menu bar. >>> The Panel The Panel contains the following items, from left to right: 1. the active cell or cell cursor location 2. an icon area, containing the "cell deletion" icon and the "data entry" icon (the X and check-mark icons, respectively) 3. the edit area, in which you enter data, consisting of two 50 column lines. The panel also may contain up to three additional icons, and these indicate various states. First, the "Circ" icon may appear should you enter a formula that contains or makes a circular cell reference (this icon may show up as "???" if Opus can't determine circularity- more on this later). Second, if the cell cursor is moved into a hidden cell, the "H" icon will appear. Finally, the "P" icon appears when the cell cursor is in a protected cell. A click on the "Circ" icon will present you with an alert box indicating the cell containing the circular reference, while clicking on the "H" or "P" icons will unhide or unprotect the active cell. If you want to delete the currently active cell, click on the cell-deletion icon. Similarly, to complete data entry into a cell, click on the data entry icon or press RETURN, ENTER, or any of the cursor keys. >>> Data Entry Opus supports the three traditional spreadsheet cell classes: numbers, labels, and formulas. Unlike other spreadsheets which require you to precede a label with the apostrophe or formulas with plus or equal signs, Opus uses the function keys F8, F9, and F10 to change cell class. You may also perform this action from the Edit menu. Look under the Edit menu now, and note many items have keyboard equivalents. All menu items with corresponding keyboard commands have the commands listed to their right. If you're unsure of the meaning of some of the symbols, please look under the Help menu item and click on the Keyboard entry. Here, you will also find all the ways you can move about the spreadsheet. For a list of the various mouse functions, please refer to the Help item Mouse. March 12, 1989 p. 3 Opus v. 2.00 >>> Cell Format Opus offers many options for cell format, and they are found under the Edit menu item. All but the number formatting options are found in the same dialog, and both of these dialogs reflect the state of the active cell when they are first displayed. To display this dialog, click on Justification under the Edit menu. The Justification button will be selected, indicating that this parameter is the one that will be changed. In order to alter the text style, for example, you must select that button as well. Now, consider the "extent" buttons, which allow you to specify whether the format changes should affect only one cell, a range, or the entire worksheet. For example, to change the justification of a range without altering other formatting within the range, make sure that the Justification button is the only one selected when you click on OK or press RETURN. Please note that the sparse matrix design requires any cell containing data or a format differing from the global format to *exist*, which means that it consumes memory. This makes it impossible to format an arbitrarily large range. However, you may certainly change the default cell format through the "Global" option, affecting all existing cells and all cells entered thereafter. >>> Number Format Now, pull down the Edit menu and click on Number. This dialog functions just like the previous one; to select an attribute to be changed, you must click on its title. For example, to turn off commas, click on the line "Suppress Commas?", click on the box to its right (checking it), and then press OK or hit RETURN. Likewise, if you wish to change the precision, click on the "Precision" title. The "Format Strings" option allows you to specify a string that will be output on all numeric or formula cells possessing that attribute. For example, you could specify a format string "Part #", and any cell having that as part of its number format would be display as "Part #xxx", where xxx is its value. You can use the reverse apostrophe "`" (the key to the left of Backspace) to specify the value position within the format string; the default is to append the value to the end of the string. In order to make a new format string, click on the "Edit box," and then type in the string. When you're done, click on "Add." The string will appear in the scrollable list. To make the string part of a cell's format, click on the string within the scrollable list and also on the "Format Strings" title before exiting the dialog. The "Global Upper and Lower Limits" fields contain the values above and below which the cells will display as scientific notation. For example, if the global lower limit is 1E-3, any cell containing a value whose magnitude is less than 0.001 (but not equal to zero) will be displayed in scientific notation. Note: Many Opus dialogs use a worksheet range as a parameter. If a range was selected before the dialog was invoked, that range will appear in the "Begin" and "End" fields in the dialog. In the case of the format dialogs, the "Range" button will also be preselected. If a range was not selected, however, the extent of March 12, 1989 p. 4 Opus v. 2.00 the format dialogs will be set to "Cell," meaning that the active cell alone will be affected (provided you don't override this). In the case of the Number format dialog, the "Use All" button will be preselected as well, so that you needn't click on all the attribute titles you want to alter. >>> Block Commands A block or range is simply a rectangular group of one or more cells. You can select a block by dragging the mouse or clicking on the Start and End Block items under the Block menu. If you're using the mouse, the worksheet will scroll if you move off the working area. When a block is selected, several worksheet functions become available. The Show First Cell and Show Last Cell items under the Marks menu change to Show Block Start and Show Block End. Under the Block menu, Copy, Move, and Delete Block become available. Before discussing the items under the Block menu, let's take a look at the difference between relative and absolute cell references. >>> Cell References Cell references within formulas are divided into relative and absolute types. A relative cell reference is written as A1, while absolute cell references are written as $A1, A$1, or $A$1. The dollar sign indicates whether the row or column part of the reference is to be considered absolute, meaning that it is "cast in stone" and will never be altered by any worksheet function, such as Move Block, Replicate Cell, or Insert Row. To clarify, consider the worksheet below: A B 1 1 A1+1 2 B1+1 A2+1 If you selected the range A1:B2 and then chose to move it to cell A3, the resultant worksheet would appear as follows: A B 1 2 3 1 A3+1 4 B3+1 A4+1 As you can see, the relationships between the formulas have remained intact. Were those cell references absolute, they would not have been altered by the move. Note that several worksheet functions give you the option to consider *all* cell references as absolute, and these include Copy and Move block, Insert and Delete row/column, and Replicate Cell. March 12, 1989 p. 5 Opus v. 2.00 >>> Copy and Move Block These functions, along with Delete Block, are only available when a block is selected. So, to copy or move a block, first select one, and then move the cell cursor to the cell you wish to be the upper-left corner of the destination block. When you choose one of these, you will first be asked to confirm your selection, as there is no "Undo" function. Then, you will be asked whether to treat all cell references as absolute, including the relative ones. Generally, you'll want to choose "Relative," so that only the true absolute references will be considered absolute. And in any event, a relative reference will only be adjusted provided it points to a cell contained within the selected range, which consequently also changes position. As a final point, be aware that cells *outside* the source range containing formulas with cell references pointing within the source range will *not* be altered, even if the range is moved. For example, suppose cell F1 references cell A1, and you move the range A1:B2 to cell A3. F1 will continue to reference cell A1. >>> Delete Block Permanently deletes a block. >>> Insert and Delete Row/Column These functions allow you to specify whole or partial row and column insertion and deletion. As an illustration of "partial," a partial row is defined as follows. First, if no block is selected, the partial row extends from the active cell to the rightmost cell in that row. If a block is selected, then the partial row extends from the upper-left cell in the block to the rightmost cell in that row and within the block. For the sake of the operation, a "virtual block" is defined as consisting of the partial row plus all partial rows below it. A partial column is defined in an analogous manner. This allows a rather flexible definition of the extent of these operations, so that, for example, it's easy to insert a row at row #18, confined to columns F and G, rather than extending over the entire worksheet space (columns A..IU). Without the "partial" option, you would have to select the range F18:G998 and then move it to cell F19. Note: These operations are really block moves, and the description of the handling of cell references for block moves applies here as well. >>> Data Fill This function fills a range with numbers, beginning at some initial value to which some increment value is added for each cell. You specify the direction of the data fill as "Right" or "Down." March 12, 1989 p. 6 Opus v. 2.00 >>> Replicate Cell This function copies a cell throughout a range. If the cell contains a formula, then relative cell references are adjusted, provided you haven't click on the "Absolute" button in the dialog. Note that it doesn't matter whether cell references point to cells within the selected range, as it does for block copying and moving. >>> Sort This function uses the ShellSort algorithm to sort a range on a row or column basis. For example, consider the range A1:C10, which is to be sorted by row. For "Key Cell," I specify cell B1, meaning cells in column B are compared. Then rows 1-10 are sorted based on the values in column B, for columns A-C. You may also specify ascending (low to high) vs descending (high to low) as the "sense" of the sort. The precedence of cells is as follows, from lowest to highest: 1. Empty cells 2. Values (numeric or formula cells) 3. Labels. Note that relative cell references in formulas aren't affected by the sorting operation (in other words, any cell reference is treated as if it's absolute). >>> Auto Cursor To illustrate this feature, select a range and position the cursor anywhere within it, except the last cell. Now press RETURN, and observe, the cursor advances to the next cell. You may specify the direction for the auto cursor through the Options menu, and you may also turn it off. This feature comes in really handy when you have a lot of numbers to enter, as you can first select a range and then enter the data solely through the numeric keypad. The worksheet also scrolls properly if the range extends beyond the displayed portion. And that about does it for the block operations. Let's forge ahead and consider formulas and functions, but first a few words about recalculation modes. >>> Recalculation Opus provides natural order recalculation, meaning that during evaluation of a formula, any cell references are calculated before their values are used. This ensures that formulas containing references to other cells are calculated based upon up to date values. Opus also provides an automatic recalculation feature, meaning that if you change the value of a cell that is referenced by some formula, that formula will be recalculated automatically. This is a little different from other spreadsheets that provide a similar function, in that Opus doesn't recalculate the entire spreadsheet, March 12, 1989 p. 7 Opus v. 2.00 but rather, just those cells that are affected by the change. This method (also called minimal recalculation) can be much faster for large worksheets and literally makes this a usable feature. How does Opus know what cells are affected? Briefly, each cell that is referenced by a formula has a "dependent cell list," and when you change the value of such a cell, Opus can traverse this list and recalculate all the other cells that depend on the cell's value. Note that having a dependent cell list requires a cell to exist, meaning it consumes memory. Be aware that range references within formulas cause an entry to be placed in the dependent cell list of every cell within the range, and the cells will be created as necessary. This precludes the use of arbitrarily large ranges in formulas, lest you're fond of "out of memory" errors. Finally, note that you may turn off natural order and automatic recalculation through the "Options" menu. With both turned off, recalculation proceeds in a row by row fashion, which can be useful in some applications (the supplied amortization spreadsheet depends on it). Now, it may rarely be necessary to turn off these features, so that Opus may complete the recalculation; you will be informed of this with a friendly alert box. For example, consider the worksheet below: A B C...........IT IU 1 B1+1 C1+1 D1+1.......IU1+1 A2+1 2 B2+1 C2+1 D2+1.......IU1+1 A3+1 . . 100 B100+1 C100+1 D100+1.....IU100+1 1 In order to calculate cell A1 using natural order, the value of cell B1 must be known. But to calculate B1, the value of C1 must be known. And so on, for 25,500 cells. Essentially, this involves a recursive algorithm, that is, a function that calls itself. If this function was allowed to call itself 25,500 times without returning in the meantime, the machine would surely crash. But don't worry, this can't happen in Opus 2.00; at worst, you will be informed of this state with an alert, "Stack is nearing overflow...", and you should then turn off natural order and/or automatic recalculation. In general, you'll never see this alert, as it requires a fairly large and somewhat contrived spreadsheet before it appears. This worksheet also confounds determination of circularity for similar reasons; it most definitely will cause the "???" icon to appear in the Panel. >>> Global Recalculation When you select "Recalculate" from the "Options" menu or press F1, Opus recalculates the entire spreadsheet, and this is called a global recalculation. Natural order will be used, provided it hasn't been turned off. However, the state of the automatic recalculation mode isn't relevant here, since we're recalculating the entire worksheet. March 12, 1989 p. 8 Opus v. 2.00 >>> Formulas Formulas in Opus consist of valid arithmetic expressions, composed of the following: - numbers, followed by an optional percent sign - cell references - arithmetic operators +, -, *, and / - logical operators =, <>, <, <=, >, >= - unary minus, "-" (i.e. negation operator) - functions and their parameter lists, but without the silly '@' sign required by other spreadsheets - expressions in parentheses. Numbers have 17 decimal digits of precision, and the range is +/- 1E-37 ... +/- 1E37 or thereabouts. At present, Opus doesn't support strings in formulas or string functions; a future update likely will. The maximum formula length is 100 characters. Opus follows the usual rules of operator precedence, summarized below, from highest to lowest: - unary minus - expressions in parentheses - *, / - +, - - =, <>, <, <=, >, >= Operators with equal precedence are evaluated left to right, so that 6/3/4 is interpreted as (6/3)/4, rather than 6/(3/4). >>> Functions The heart of any spreadsheet lies in its list of functions; Opus provides some 59 functions, which I will divide into the following categories: Arithmetic, Power, Trig, Logical, Statistics, Regression, Probability, Financial, Lookup, Cell, Range, and Miscellaneous. Please note that range references are written as two cell references separated by the colon, as in "A1:F5". >>> Arithmetic - DIV, MOD (numerator, denominator) These are division and modulus functions that satisfy the equation below (for both real and integer values): x = DIV(x,y)*y+MOD(x,y) - ABS (expr) Returns the absolute value of expr. March 12, 1989 p. 9 Opus v. 2.00 >>> Power - LN (expr)..............natural logarithm (base e) - LOG (expr).............log base 10 - EXP (expr).............e raised to a power - POW (expr1,expr2)......expr1 raised to expr2 power - SQR (expr).............square - SQRT (expr)............square root >>> Trig All the trig functions (except RAD) expect angles to be specified in radians, and the inverse trig functions return a radian value. - SIN, COS, TAN (angle)........sine, cosine, tangent - ASIN, ACOS, ATAN (expr)......inverse functions - SINH, COSH, TANH (angle).....hyperbolic sin, cos, tan - ASINH, ACOSH, ATANH (expr)...inverse functions - RAD (angle in degrees).......returns angle in radians - DEG (angle in radians).......returns angle in degrees - PI().........................returns pi >>> Logical Operators: =, <>, <, <=, >, >= IF (condition, action, alternate action) The three IF parameters may be any valid expression, including nested IFs. IF returns the value of "action" when condition evaluates to non-zero, and it returns "alternate action" when condition evaluates to zero. AND (expr1, expr2, expr3, ...) Returns 1 if all parameters are non-zero, and 0 if any evaluate to zero. OR (expr1, expr2, expr3, ...) Returns 1 if any parameter is non-zero, and 0 only if all evaluate to zero. NOT (expr) Returns 1 if expr evaluates to zero, and 0 if expr evaluates to non-zero. Both AND and OR require at least two parameters. >>> Statistical - SUM (range) Computes sum of all values within range. Empty cells and labels are considered to have value 0. March 12, 1989 p. 10 Opus v. 2.00 - PROD (range) Computes product of all values within range. Empty cells and labels are considered to equal 1. Should the range contain no values, PROD returns 0. - MEAN (range) Computes the mean or average of all values within range. Empty cells and labels aren't considered. - VAR (range) Computes the sample variance for range, ignoring empty cells and labels. - SDEV (range) Computes the sample standard deviation for range, ignoring empty cells and labels. - SERR (range) Computes the sample standard deviation of the mean (the standard error) for range, again ignoring empty cells and labels. - MAX, MIN (range) Return the maximum and minimum values within the range. - COUNT (range) Returns the number of cells containing values within range. >>> Regression Note that these three functions all require the "Type" parameter, which is explained under REGR. - REGR (type, y-range, x-range) Performs linear regression via the least squares method on any of the following models: Type Equation Model 0 y = Mx+B Linear 1 y = Be^(Mx) Exponential 2 y = B+M*ln(x) Logarithmic 3 y = Bx^M Power Please note that Opus performs the proper transformation on the data for you, so you aren't required to have a separate column for e^x to use the exponential model, for example. REGR returns the value "M" in the cell containing the formula and the value "B" in the cell March 12, 1989 p. 11 Opus v. 2.00 immediately to its right. "B" will overwrite this cell, so make sure you store no data there! - PREDV (type, y-range, x-range, x-expr) This function calculates the value "y" based on the regression parameters M and B for the value "x-expr". Be aware it is more time and memory efficient to simply plug the number into the proper equation, provided of course you have already determined M and B through REGR. - CORR (type, y-range, x-range) CORR rounds out the regression functions. It calculates the correlation coefficient, which is a measure of goodness of fit. The regression functions allow empty cells within their ranges. X and y values are associated by their cell locations within their respective ranges, not by the number of empty cells that may separate them. For example, consider the range A1:A5 below: A B 1 1 2 empty 3 empty 4 2 5 3 For the sake of the regression calculation, value 1 is cell A1, value 2 is cell A2, and so on. It is perfectly legal to have an x-value without a corresponding y-value; that x-value will simply be discarded from the calculation. However, the reverse is not true; should you specify a y-value without a corresponding x-value, any of these functions will return an error. I chose Opus to work in this manner because in my work, I'm often collecting sets of data from several trials of the same experiment, where the known values are the same from trial to trial. Occasionally, during a trial one of the data points gets botched, and it should be discarded from the calculation. By simply deleting the cell which would otherwise contain that y-value, I can use the same template for analyzing all the data sets. (I wish my Hewlett-Packard calculator worked this way; instead, it forces me to delete any x value without a corresponding y value, altering the relationships between other data sets which may be in its memory) Finally, all the regression functions allow ranges spanning more than one column or row. Values are associated on a row by row basis. >>> Probability RAND (lower bound, upper bound) Returns a random number between the given lower and March 12, 1989 p. 12 Opus v. 2.00 upper bounds. The difference between these two numbers must be less than 16,277,216, since this is the range of the ST's random number generator. COMB, PERM (x, y) Combinations and permutations of x objects taken y at a time. >>> Financial These functions operate somewhat differently from those in the original version of Opus. First, all parameters are required. Second, I've adopted a convention taken by my HP- 27S calculator and also, at least, by the Microsoft spreadsheet Excel. This involves breaking down money values into cash inflows, which are expressed as positive numbers, and cash outflows, expressed as negative numbers. For example, the PMT function will normally return a negative value, as you are "paying money." I found this method confusing at first, but I grew to prefer it, and since I (occasionally) like to support standards... The "type" argument appears in all the financial functions, and if equal to 1, it indicates payments occur at the ends of periods (ordinary annuities). If type equals 0, payments are assumed to occur at the beginning of periods (annuities due). Note that for some combinations of arguments, namely those implying a simple or compound interest calculation, the type field will be meaningless; nevertheless, it is required as a place-holder. The number of compounding periods should be whatever is most appropriate; for example, 365*n for daily compounding over n years. The rate arguments refer to the interest rate per compounding period, so for monthly compounding over 1 year at 12% interest, rate would equal 12%/12, or 1%, while # periods would equal 12. For working, real world examples of the financial functions, I refer you to the files "FINCALC.OPS" and "AMORTIZE.OPS." - PV (rate, # periods, payment, future value, type) Computes present value. - FV (rate, # periods, payment, present value, type) Computes future value. - NPER (rate, payment, present value, future value, type) Calculates number of periods. - PMT (rate, # periods, present value, future value, type) Calculates payment. March 12, 1989 p. 13 Opus v. 2.00 - RATE (#periods, payment, present value, future value, type, guess) Computes interest rate. RATE uses an iterative method (Newton's) to find rate; it requires a "guess value" to seed the process, and you should try using a value less than what you expect RATE to return. (Good starting points for guess are values like 0.01, 0.001, etc.) RATE returns an error if it can't find a reasonably accurate solution within 20 iterations. The financial functions are based on the following equation, and RATE successfully returns if it finds an interest rate that satisfies the equation to an accuracy of 1E-8. (Equation from Hewlett Packard 27S calculator manual) 0 = PV+(1+(i%*S)/100)*PMT*USPV+FV*SPPV, where S = payment mode (0 for end mode, 1 for begin mode. Note this is exactly opposite to what the functions expect as an argument; the value 1 seemed more logical than 0 to indicate a date later in the period.) i% = periodic interest rate n = number of compounding periods SPPV = (1+i%/100)^-n USPV = (1-(1+i%/100)^-n)/(i%/100) >>> Lookup - INDEX (row index, column index, range) INDEX returns the value of a cell within range, located by row and column index, which must be numbers greater than or equal to one. These indices represent offsets into the range, such that the upper-left corner of the range has 1,1 for its indices. For example, INDEX(1,1,A1:B5) returns the value of A1, while INDEX(3,2,A1:B5) returns the value of B3 (row 3 and column 2 within the range A1:B5). - VLOOKUP (value, column index, range) VLOOKUP searches in the first column of the indicated range for the greatest value less than or equal to the value you supplied, and it returns the value in the same row as this cell, with the column determined by "column index" as an offset into the range. Like INDEX above, a value of 1 indicates the first column within the range, 2 the second, and so on. The function is a "vertical lookup," as it searches in the vertical direction. An error occurs if no match is found or the index references a column outside the block. March 12, 1989 p. 14 Opus v. 2.00 - HLOOKUP (value, row index, range) This function is exactly analogous to VLOOKUP, except that it performs a horizontal lookup. That is, it searches the first row of the indicated range, looking for a value less than or equal to the value you supplied, and it returns the value in the same column as this cell but in the row indicated by "row index." Again, the row index is an offset into the range, such that row index = 1 indicates the first row of the range. >>> Cell - ISERR (cell ref) Returns 1 if the cell referenced has an error status and 0 otherwise. - ROW, COLUMN (cell ref) Return the row and column number of the argument. >>> Range - ROWS, COLUMNS (range) Return the number of rows or columns in the range supplied. >>> Miscellaneous - FAC (expr) Computes the factorial of expr, which must be an integer such that 0 <= expr <= 33. - ROUND, TRUNC (expr, place) These functions take an expression and either round or truncate it to the value specified by "place." Place may be positive, negative or zero, and I think an example will clarify the differences. Consider the number 126.556, supplied to ROUND and TRUNC, for the following values of place: expr = 126.556 place ROUND TRUNC 2 126.56 126.55 1 126.6 126.5 0 127 126 -1 130 120 -2 100 100 -3 0 0 As you can see, you can round or truncate within the whole number portion of the expression, as well as within the fractional portion. March 12, 1989 p. 15 Opus v. 2.00 >>> Cell Status Every living cell has an associated status which tells Opus whether it's full, empty, or for some reason generated an error. Error-trapping in formula evaluation is extensive, and I think, complete. For example, if a formula caused a division by zero, the cell will display a "DivBy0" error message, and any cell that referenced it will also assume this status upon recalculation. There are several other error messages, and they are used depending on the nature of the offense. The syntax error is a special case; should you enter a formula that's semantically incorrect, Opus will "keep you in that cell" and (usually) place the cursor near the source of the error in the edit area. Users of the original version will be glad to hear that Opus will no longer crash upon floating point overflows; this was an additional benefit of putting Personal Pascal on the shelf and rewriting Opus in Mark Williams C. Now, floating point overflows will display as "a very large number." There remains only one loose end in the error-checking; Mark Williams C is supposed to set a certain variable when the library function "pow" overflows, and it doesn't. Thus, the spreadsheet function POW and several others, including the financial functions, will generate "a very large number" upon pow overflow, and the cell status won't reflect the error condition. Hopefully, MW Co. will correct this in a future compiler update. >>> Named Cell and Range References Opus v. 2.00 and above support named cell and range references, so that you may give a cell or range a friendly English-language name for use within formulas. These "aliases" may be up to 10 characters long; they consist of alphanumeric characters and the underscore and may not begin with a numeral. Also, you aren't allowed to create a name that duplicates a valid cell reference or a function name. Opus supports as many as 100 of these aliases, and you create them through the Define Name dialog, which is found under the Options menu. To use this feature, enter the name you wish to define in the "Name:" line and also the cell or range reference (using dollar signs to indicate absoluteness) in the "Refers To:" line. Then, add it to the list by clicking "Add." The name will appear in the scrollable list (which is always sorted), and it will be available for use in functions. To delete a name, click on it and then click "Delete." It will be removed, and all occurrences of that name within the worksheet will be replaced by the underlying explicit cell or range reference. Note that when you click on one of the names in the list, Opus places that name and its value in the two editable fields below the list. As long as you don't alter the name itself, you may then modify the "Refers To:" line and click on "Add" to lock in the modification. When deleting or altering names, there may be a slight delay as Opus performs some housekeeping (converting names to explicit references, validating what in effect may be completely new formulas, updating dependency lists, etc.). Bear in mind these named references behave exactly like explicit ones, following the same rules governing adjustment for worksheet operations such as copy, move, insert row, and others previously described. You may March 12, 1989 p. 16 Opus v. 2.00 notice when copying, moving, or replicating formulas that Opus substitutes the explicit reference for the named reference. This happens when a named reference needs to be adjusted; there just isn't any good way to make a single name point to more than one cell or range! However, this substitution will not be applied to completely absolute named cells or ranges, since these are never adjusted. >>> Files You may save and load whole worksheets and blocks; block files consist solely of data, while worksheet files contain the data, all the user settings, and the four charts. A block may be merged into the current worksheet, while loading a file causes the current worksheet to be erased. File operations are much faster in Opus 2.00, largely due to use of a custom 10 sector buffering scheme. In other words, Opus always reads or writes 10 sectors worth of data when it accesses the disk, unless of course there simply isn't enough data to fill 10 sectors. The speed increase is truly remarkable, and to take full advantage of it on floppies, be sure to use a "twisted" disk formatted for 10 sectors/track. Please note that Opus 2.00 files are not compatible with the original; too many fundamental changes were made. However, I will maintain compatibility with this version in future updates. >>> Printing You control worksheet printing through the Print dialog, found under the File menu. You may enter two title lines, and these will appear on the first page only. Opus supports one-line headers and footers; you may easily include such things as page number, file name, date, and time, and any part of a header and footer may be left, right, or center justified. To see how to accomplish this, please refer to the Help menu item Print/Save As Text. The only really new features here are the margin and lines/page fields; margins are specified as number of characters or lines from the respective side of the page. For example, a right margin of 5 will leave a 5 character margin on the right side of the page. The other Print dialog options should be reasonably self-explanatory. In order for features such as condensed print and draft vs. final to work, Opus needs to know the proper control codes for your printer. Since these are everything but standardized, I've included a program, PRINTDEF.PRG, so that you may customize Opus for your printer. Please see the file INSTALL.DOC for details on PRINTDEF. To wrap up this subject, you may also save a file as text, which really means print a standard ASCII file to disk. This file will include titles, headers, footers, etc., but it will not contain any text special effects (naturally). March 12, 1989 p. 17 Opus v. 2.00 >>> Freeze Titles To freeze a row and/or column, position the cell-cursor in the *last* row or column on the screen you wish to freeze. For example, suppose you have rows 5 through 20 on the screen, and you want to freeze rows 5-15. Place the cell cursor in row 15, and choose Freeze Titles from the Options menu. Select Row and press OK. Now, you may scroll downwards, while the frozen rows remain on screen; you are also prevented from advancing the cursor above row 16. This can be very useful when you have labels over several lines that you'd like to keep in view at all times. Although freezing affects the screen appearance, it has no effect on printing. >>> Defaults Opus 2.00 allows you to save your favorite settings in a configuration file, OPUS.CNF, which is loaded at boot-time. This file contains default path information, worksheet options, and chart options. You may change the defaults and save a new configuration file through the Defaults item under the File menu. To change paths, click on the path lines and select a new one with the item selector. Besides the paths, OPUS.CNF contains the following items: - global column width - global cell format - auto-cursor status and direction - natural order and automatic recalculation statuses - show formulas status - grid on/off - small font (for monochrome) - printer: - show row/column titles - condensed print status - show formulas status - header - footer - draft vs. final - top, bottom, left, and right margins - lines/page - charts: - all user-controlled options (except selected ranges), taken from current active chart Note: The Temporary Files path refers to the path where the temporary metafile and worksheet files will be saved during chart printing. More to come... March 12, 1989 p. 18 Opus v. 2.00 /////////////////////////////////////////////// ///// Charts ///// /////////////////////////////////////////////// NOTE: If GDOS isn't installed, you won't be able to chart. If you aren't sure how to create a proper ASSIGN.SYS or OPUS.WID file, please see INSTALL.DOC for instructions (it's really pretty easy, as I've written two short programs to facilitate the process). >>> The Basics The charting facility is implemented as a mode separate from the worksheet. To create a chart, you first select ranges from the worksheet for the chart data sets, and then select To Chart from the worksheet Chart menu. This takes you to a new screen and menu bar, from which you may customize the chart's appearance and print it. Opus displays the chart in a window whose maximum size is 8 inches wide by 5 inches tall, and the screen display is a very close approximation of the final printer output. Finally, to get back to the worksheet, select To Opus from the chart File menu. Note that you can easily flip back and forth by pressing the control-C key. In the following sections, I'll describe some of the charting conventions. Since I feel the charting features are mostly intuitively obvious, afterwards I will simply run through the menu items and explain some of the subtler points, leaving the rest to experimentation. However, it is probably a good idea to read the section on saving metafiles and printing charts, which are found under the "File" heading. >>> Axis Naming Conventions All chart types except Pie are essentially plots of the equation y = f(x), where y is a variable that depends on the value of x. X is typically associated with the horizontal axis and y with the vertical, but since Opus allows rotation of the axes, this distinction can become blurred. Since x is more properly referred to as the "independent variable" and y as the "dependent variable," I call the axes "Dependent Axis" and "Independent Axis." >>> Data Series A data series is simply a set of values associated with an axis variable. The Independent Axis may have only one associated data series, but you may specify up to six Dependent Axis series, identified by the letters A-F. To select a range as a data series, first select a worksheet range, drop down the worksheet Chart menu, and click on the desired item under the greyed-out "Data Ranges" label. A small dialog appears, containing the range definition. Press OK to complete the process, and the chosen menu item will be checked to indicate it's in use. To delete a series, March 12, 1989 p. 19 Opus v. 2.00 click on the appropriate menu item and click on the Clear button within the select-range dialog. In order to produce a Pie chart, you must first select a range for the Independent/Pie series (this one does double-duty). To produce any of the other chart types, you must select at least one dependent variable range. The dependent and independent variables are associated exactly as for the worksheet regression functions. That is, ranges may extend over more than one column; they are associated on a row by row basis. Also, it is perfectly legal to have an independent value without a corresponding dependent value, but the reverse is not true. Finally, you may specify labels for the independent range for any chart type except Pie; if the first cell within the independent range is a label, all the rest must also be labels. The labels have implicit values of 0, 1, 2, ... >>> Plotting Standard Error Bars and Regression Lines These may be automatically plotted, providing you've created the formulas in the worksheet. Simply associate the ranges with the appropriate data series. Note that for regression, you must select the slope and y-intercept cells as a range, and the slope must be the first cell in the range. >>> The Screen Display The size of the chart as displayed on the screen is very nearly the same as the final printed size, and the relationships between objects are practically identical between the screen and printer. When you alter the chart size, you will find that the window containing it expands or shrinks, and it is centered at all times. The window size corresponds to the chart area, with a 0.1 inch margin around all sides. It also reflects the "frame" that will contain the chart when it's imported as a metafile into another program. Since redrawing the screen can take a couple of seconds, I thought it preferable to redraw the screen only when requested. Thus, you may make many changes affecting a chart's appearance, and when done, press 'D' to force a redraw. About the only time the chart is drawn without the user's request is when he flips over from the worksheet, changes the chart size, or selects a new chart with the chart switcher. >>> Markers The objects indicating plotted points are called markers. For line and scatter charts, the markers are as follows: data series A: circle, B: square, C: up triangle, D: cross, E: down triangle, F: plus. Bar, pie, and area markers are differentiated on the basis of fill pattern. Be aware that in color, the circle marker may appear as a plus sign at the standard size of 0.08 inches due to March 12, 1989 p. 20 Opus v. 2.00 the limited resolution, but it will print fine (details on altering the size follow). >>> The Chart Switcher Opus supports four charts per worksheet, and you select them through the Chart Switcher dialog. This dialog is accessible from both the worksheet Chart menu and the chart File menu. To restore a chart to the default settings and clear all range definitions for that chart, click on the Restore Defaults button. >>> Measuring Many dialogs allow you to alter the sizes of objects; Opus uses inches for all measurements. >>> The File Menu A. Save Metafile... Opus is capable of saving two types of metafiles, a standard one (.GEM) suitable for programs that read metafiles, like Publisher ST, and a special one (.GEO) intended for later printing by OutChart. Opus will ask you to specify the format before allowing you to choose a file name; choose "Standard" if you intend to load the metafile from another (unrelated) application and ".GEO" if you plan on printing the file from OutChart. Note: OutChart doesn't like standard metafiles at all; please feed it .GEO files, unless you enjoy "Corrupted Metafile" error messages (read on for explanation). Although programs like Publisher ST allow scaling of imported metafiles, for best results you should keep the relative horizontal and vertical dimensions the same. You may notice that the square marker types vary in size somewhat in a metafile imported into Publisher, even though the chart is set to the right size. This is simply a consequence of round-off error in calculating the size of the box on the screen (although the box is a square by metafile standards, some round-off error occurs depending on where the box is to be located on the screen or page). As you would expect, this effect decreases in significance as the resolution of the output device increases; that is, it's most noticeable on the color monitor and hardly noticeable on a 150 DPI printer. Before printing a chart, Opus saves a temporary metafile which it later interprets; Opus isn't afflicted with similar round-off errors because it uses some special metafile commands to ensure uniform sizes for markers. OutChart metafiles contain these special commands as well. Unfortunately, other programs wouldn't know how to interpret these special commands, so "Save Metafile" can also save a standard one that should be March 12, 1989 p. 21 Opus v. 2.00 compatible with any program that claims to load metafiles. B. Print... Prints the chart. An option for a final formfeed is present, since some printer drivers execute a formfeed when Opus closes the printer workstation, but others don't. For details on sizing the chart and placing it on the page, please refer to Chart Dimensions under "The Edit Menu." See the file OUTCHART.DOC as well for an alternative to printing from within Opus. To conserve memory, Opus loads the printer driver and fonts at print-time. The process is as follows: 1. Opus saves a metafile and the worksheet, in the path specified for Temporary files 2. Opus releases the worksheet memory and screen font memory to the system, 3. Opus loads the printer driver and fonts, 4. Opus reads in the metafile and prints the chart, 5. Opus releases the printer driver and font memory, 6. Opus reloads the screen fonts, 7. Opus reloads the worksheet, 8. Opus deletes the temporary metafile and worksheet file. For this to work, several conditions must be satisfied. First, you must have your GDOS disk in the boot drive or have the files set up on a hard drive. Second, you must specify a drive with enough free space to store the temporary metafile and worksheet files (metafiles typically range 2-10K; worksheet files vary considerably more). Third, you must have enough free RAM in the system to load the printer driver and fonts. FONTWID.PRG provides this information, when you create your OPUS.WID file. When you first load Opus, before entering any data, check Statistics under the worksheet Options menu and make sure the System Memory is greater than or equal to the memory required to print, as given by FONTWID. Although printing is a rather disk-intensive process, it really is pretty fast on a hard drive system. For best results on any system, set the Temporary Files path to a RAM disk, but make sure you have enough free RAM to print! Finally, I should note that the ST's memory allocation system is flawed. Under some essentially unpredictable conditions, after printing you may find yourself with less worksheet RAM than before. This is due to memory fragmentation and is generally not a problem, unless your worksheet is already pushing the free RAM limits. In this case, you may find yourself with too little memory to reload the worksheet. To protect yourself from this, always save your worksheet before printing a chart. Fortunately, the fragmentation seems to occur only with the first printout; I've printed more than 10 March 12, 1989 p. 22 Opus v. 2.00 charts in a single session with no problems beyond losing 30K of worksheet space due to the fragmentation. C. Load/Save Chart Presently not implemented, since four charts are saved with the worksheet. If there's enough demand, I may add these in a future update. D. Chart Switcher... Allows you to select any of the four charts. To simply switch from one chart to another without calling this dialog, press the appropriate number key. >>> The Edit Menu A. Axes Allows you to fine-tune the axis appearance as needed. To switch from editing one axis to the other, click on the shaded title bar at the top of the dialog. I believe all the options are pretty self-explanatory, except "the axis crosses other axis at tic mark#" option. Opus always tries to determine a "nice" place for the axes to cross one another. You may override the default choice by clicking on the number field. This will highlight it and enable the up and down arrows beside it. You may then increase or decrease the value by clicking on the arrows. Note that tic# 0 refers to the lowest tic on the vertical axis and the leftmost tic on the horizontal one. B. Chart Dimensions You may create charts of any size up to 8 inches wide by 5 inches tall. You may specify the placement of the chart on the page through the left and top margin values. Some printer drivers support only an 8x10 inch area, such as my Migraph Deskjet drivers. Thus, to horizontally center a chart 7 inches wide and 5 inches tall, I specify 0.5 inches as my left margin (left margin = (8-7)/2). To vertically center the same chart, I specify 2.5 inches as the top margin (top margin = (10-5)/2). Some printer drivers may allow printing to the entire 8.5 inch width of a page (or 11 inch height), so you may have to experiment a bit to determine the proper offsets. Remember, when you create a chart AxB inches in size, these numbers include a 0.1 inch margin around the entire chart area. C. Legend A legend allows you to give a label to each of the data series on multiple-series charts. The legend may appear to the right of the chart or below it, and the "legend labels" are preceded by the marker associated with the March 12, 1989 p. 23 Opus v. 2.00 series. To change the size of these legend markers, enter a new value into the Chart Dimensions dialog under the "Marker Size" field. For bar, pie, and area charts, the marker is a small filled box, and the size of these markers is twice the size entered under Marker Size (I did it this way so I could easily flip between scatter and bar charts and not worry about getting huge chart markers or tiny legend markers). The Edit button allows you to create or modify the legend labels. You will note 12 lines in this dialog; the last six are for Pie charts, where each slice may have a legend entry. When you select a range for legend text from the worksheet, the labels are copied into the legend text array and are from that point separate from the worksheet. D. Pie Appearance You may have pie slice values, percentages, and legend labels appear by the slices or within the legend, in various combinations. If you choose "By Slices" for some of these and have the standard legend appear to the right of the Pie, the slice labels may overlap the legend (sorry, but this is the only case where the chart doesn't get out of the way properly. Maybe next revision). To correct for this, you may enter a larger value for the Legend distance into the Chart Dimensions dialog. E. Scaling Opus generally selects a nice numeric range for your data. To override the defaults, invoke the scaling dialog and click on the entry you wish to change (you may not edit it otherwise). It will be highlighted, indicating user settings are in effect. F. Titles Opus provides two-line titles for each axis and the chart itself. Independent axis titles are shown as I1: and I2:, while dependent axis titles are shown as D1: and D2:. Just as with legends, you may copy a worksheet range into the titles array. You may then edit or create new entries through the Titles dialog. To change font or special effects, click on the entry you wish to change, and the font selector will appear. To turn off titles, uncheck the box at the upper right of the title lines. G. Values by Markers If this is in effect, Opus displays the underlying value of a marker in an appropriate place for scatter, line, bar, and stacked bar charts. Use Pie Appearance to perform this action for Pie charts. March 12, 1989 p. 24 Opus v. 2.00 >>> The Options Menu The items under this menu all act as on/off switches. A. Character Spacing When on, Opus uses the information from OPUS.WID to determine the width of text on the printer. With this value, it's possible to scale the text string so that it occupies the same relative width on the screen as it does on the printer, allowing a much better screen approximation of the final output. This can be very important, since many screen fonts are much wider than their printer counterparts; it's especially important when you want to display text centered within a box, as for a chart legend, because the box dimensions are calculated based on the size of the string. Note that when turned on, characters may overlap. This can be especially bad for the vertical axis title on a color system, but remember, the true extent of the text is shown (even though it may not be readable!). Although this feature has no effect upon printing, it should be left on when saving a standard metafile. That way, object dimensions are calculated based upon printer font widths. When you import such a metafile into Publisher ST, the strings may appear to exceed the boundaries of a legend box, for example, since Publisher doesn't perform the "width scaling" on metafile text that it does on regular text. Fear not, the metafile will print correctly! If you had saved the metafile without character spacing, it would look perfect on the screen in Publisher ST, but the legend box would print too large, leaving a very noticeable gap at the right border of the box. This is a true tradeoff, and it's a consequence of the NON-device independence of GDOS fonts (I want display Postscript!) B. Regression This causes regression lines to be displayed for scatter charts, provided you have defined ranges for the regression values. Although you may perform regression on non-linear models, at present Opus only plots the linear model properly (others may be supported in future releases). C. Rotate Axes Makes the current horizontal axis vertical and the current vertical axis horizontal. D. Show Border Draws a full box around all charts except Pie. March 12, 1989 p. 25 Opus v. 2.00 E. Standard Error Bars This causes the error bars to be displayed, provided you have defined ranges for the error values. Available for scatter, line, and bar charts. >>> The Types Menu A. Area Plots an area chart. All dependent values should be either positive or negative, with no mixing (or, if anyone can tell me a meaningful way to plot an area chart with both positive and negative values, I'll try to implement it). Maximum number of independent axis values (categories): 48. B. Bar Plots a bar chart. Use Bar Spacing to vary width of bars and distance of bars from tics. Maximum number of categories: 48. C. Line Essentially a "connect the dots" scatter plot. No limit to number of points. D. Pie Plots a pie chart with up to 12 slices. You may explode any number of slices by clicking on them. Both the Chart titles and horizontal axis title are printed, if defined. E. Scatter Scatter plot. No formal limit to number of data points. F. Stacked Bar The cautions described for area charts apply here as well. >>> The Special Menu Currently, Fill Pattern is the only item available, but object oriented drawing features may appear here in a future release. To change the fill pattern for a series, select the series number from the Fill Pattern dialog (#1-6 = ranges A-F, while #7-12 refer to the remaining pie slices). Then click on the new pattern and press OK. If you are viewing a bar, pie, or stacked bar chart, simply double-click within a marker belonging to the series you wish to change; the Fill Pattern dialog will appear, indicating the chosen series. Pie slices are numbered from 1-12, counter- clockwise. March 12, 1989 p. 26 Opus v. 2.00 >>> Future Plans Although I feel this version of Opus is quite complete, there remain several things I would like to add, such as date/time and string functions to the worksheet. Also high on my list of priorities is implementation of some simple object oriented drawing features for the charting facility. Another possibility is a curve-fitting feature, which would generate a smooth curve through a series of points. Finally, I'm always open to ideas, so let me know what you would like to see. March 12, 1989 p. 27 Opus v. 2.00