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Text File | 1994-10-10 | 8.5 KB | 254 lines | [TEXT/RLAB]

INTRO: Introduction to RLaB "Our"-LaB. RLaB is a vector and matrix oriented, interactive, interpreted programming LANGUAGE. Although RLaB started as an effort to functionally replace MATLAB, the language and functions are NOT MATLAB replicas. Although the language is similar to MATLAB in some ways there are numerous differences (I hope for the better). The help file MATLAB_DIFF briefly discusses the primary differences between RLaB and MATLAB. If you are a MATLAB expert please read the MATLAB_DIFF file ASAP. The RLaB Primer is also a good starting point for new users. It is short, and provides many introductory examples. Using RLaB: To get this far you must already be running RLaB. At this point you are using the command line interface. When RLaB confronts you with the command line prompt (`>') it is ready to accept any valid statement. As soon as a valid statement is recognized, RLaB will execute it. For example > a = sqrt(2) a = 1.41 The right-hand-side (RHS) of the expression is evaluated, and the result is assigned to `a' immediately. There are several data types. You do NOT need to declare variable types, just use them (the variable(s)) in the proper context. In the previous example `a' was a scalar. In the following example `a' will be used as a matrix: > a = [1,2,3;4,5,6;7,8,9] a = matrix columns 1 thru 3 1 2 3 4 5 6 7 8 9 The previous example created a matrix and stored it in the variable (entity) `a'. The previous entity that `a' represented (sqrt(2)) is destroyed. You can use most math operators like you would in C: a + b Addition a - b Subtraction a * b Matrix Multiplication a .* b Matrix element-by-element multiply a / b Right Division a ./ b Element-by-element Right Division a \ b Left Division a .\ b Element-by-element Left Division a^b Power a.^b Element-by-element power -a Unary minus (negation) +a Unary plus a' Matrix transpose (Hermitian transpose) a.' Matrix element-by-element transpose To see all of the available functions type `what()'. Try using some: > what() abs error log10 plot3 solve acos eval logspace plprint sort acosh exist lu plptex sprintf all exp lyap plscol0 sqrt any eye max plsfile srand asin factor maxi plstyle std asinh fft mean plwid strsplt atan filter members poly strtod atan2 find min printf subplot atanh finite mini printmat sum backsub fix mod prod svd balance floor nan pstart sylv cd format norm ptitle symm ceil fprintf num2str putenv system chol fread ode pwin tan class fseek ones qr tanh clear fvscope open rand tic clearall getb pause rank tmpnam close getenv pclose rcond toc compan getline pend read trace complement hess pl3d readb tril conj hilb plalt readm triu cos ifft plaspect real type cosh imag plaxis redit union cross inf plaz replot what cumprod input plcont reshape who cumsum int plegend round whos det int2str plerry save write diag intersection plfont schord writeb diary inv plgrid schur writem diff isempty plgrid3 set xlabel disp isinf plhist show ylabel dlopen isnan plhistx showpwin zeros dot issymm plhold sign zlabel eig length plhold_off sin eign linspace plimits sinh eigs load plmesh size epsilon log plot sizeof 1st enter a matrix: > a = [1,2,3;4,5,6;7,8,9] a = matrix columns 1 thru 3 1 2 3 4 5 6 7 8 9 Then transpose it: > b = a' b = matrix columns 1 thru 3 1 4 7 2 5 8 3 6 9 Then perform matrix multiplication with the two matrices: > c = a * b c = matrix columns 1 thru 3 14 32 50 32 77 122 50 122 194 Do an element - by - element multiply: > d = a .* b d = matrix columns 1 thru 3 1 8 21 8 25 48 21 48 81 Zero out the element of a that is in the 3rd row, 3rd column. > a[3;3] = 0 a = matrix columns 1 thru 3 1 2 3 4 5 6 7 8 0 Use det() to compute the value of the determinant of [a]. > det(a) 27 Use another built-in function to estimate the reciprocal of the condition number: > rcond(a) 0.01935 > 1/rcond(a) 51.67 Use another built-in function to compute the matrix inverse: > inv(a) matrix columns 1 thru 3 -1.778 0.8889 -0.1111 1.556 -0.7778 0.2222 -0.1111 0.2222 -0.1111 Use yet another to compute the eigenvalues, and eigenvectors of [a]: > eig( [1,2,3;4,5,6;7,8,9] ) val vec Notice that eig() appears to return two variables, val, and vec. Actually eig() returns a LIST. A LIST is an entity that contains other entities. Functions that need to return more than one entity do so via a LIST. See `help LIST' if LISTs are confusing you. The members of a list are accessed via a special syntax. list . lname will reference the member of the list with a name equal to lname. For example: > eig([1,2,3;4,5,6;7,8,9]).val val = matrix columns 1 thru 3 16.1 + 0i -1.12 + 0i -8.46e-16 + 0i will return the eigenvalues of the input. If you want to save the entire list, then save it in a variable. > a = eig([1,2,3;4,5,6;7,8,9]) val vec Then you can access the members of the list: > a.val val = matrix columns 1 thru 3 16.1 + 0i -1.12 + 0i -8.46e-16 + 0i > a.vec vec = matrix columns 1 thru 3 0.232 + 0i 0.786 + 0i 0.408 + 0i 0.525 + 0i 0.0868 + 0i -0.816 + 0i 0.819 + 0i -0.612 + 0i 0.408 + 0i If you want to know what the names of the list members are you can simply type the list variable at the prompt: > a val vec Or, you can use the members function: > members(a) val vec To see what variables are in the workspace, type `who()' > who() a c pi b d pinfo A variable can be removed from the workspace, and it's memory freed, with the clear function: > clear(a, d) 2 > who() b c pi pinfo Clear returns a number that signifies how many objects were cleared from the workspace. At this point you should be starting to get an idea of some of the things RLaB can do, even though we have not yet introduced logical operators, conditional statements, looping statements, and user-functions. Please skim through all the help files that are spelled with capital letters. This will acquaint you with more features and let you know where to go for help in the future.