Otherware/Otherware_1_SB_Development.iso/amiga/misc/icalc.lzh/icalc/src/special.c

C/C++ Source or Header | 1992-01-26 | 4KB | 199 lines

/*
*    icalc - complex-expression parser
*
*    Special functions for icalc, such as sum, prod etc.
*
*    (C) Martin W Scott, 1991.
*/

#include <stdio.h>
#include "complex.h"
#include "constant.h"
#include "complex.tab.h"

extern int silent;

#define SUMMATION    1
#define PRODUCT        2
#define LOOP        3
#define VLOOP        4    /* (verbose loop) */

/*
*    General iteration function.
*
*    Used for sums, products and general iteration.
*
*/
static Complex iterate(al,how)
    ArgList *al;        /* argument list */
    int how;        /* sum, product or loop */
{
    Node *expr;        /* expression to iterate */
    Symbol *index;        /* index to iterate over */
    double *idxval, to;    /* real part of index, what to iterate upto */
    char *mode;        /* mode as string, for error message */
    Complex cplx;        /* general purpose complex variable */


    if (al)            /* agruments were passed */
    {
        expr = al->node;    /* get expression to iterate */

        if (al = al->next)    /* get upper limit */
        {
            cplx = cinteger(eval_tree(al->node));
            to = cplx.real;

            if ((al = al->next) && !al->next) /* get index... */
            {                  /* no more args? */
                (void)eval_tree(al->node);
                if (al->node->type == '=' || al->node->type == VAR)
                {
                    index = al->node->contents.sym;

                    if (index->type != VAR)    /* undefined */
                        index->type = VAR;

                    switch (how)    /* initial */
                    {
                        case SUMMATION:
                            cplx = zero; break;
                        case PRODUCT:
                            cplx = one; break;
                        case VLOOP:
                            if (!silent)
                                fprintf(stdout, "%5.5s =", index->name);
                            break;
                    }

                    idxval = &index->u.val.real;
                    index->u.val.imag = 0.0;

                        for (; *idxval <= to; (*idxval)++)
                        switch (how)
                        {
                        case SUMMATION:
                            cplx = cadd(cplx,eval_tree(expr));
                            break;
                        case PRODUCT:
                            cplx = cmul(cplx,eval_tree(expr));
                            break;
                        case VLOOP:
                            cplx = eval_tree(expr);
                            if (!silent) {
                                fprintf(stdout, "\t%5lg  ", *idxval);
                                cprin(stdout, NULL, "\n", cplx);
                            }
                            break;
                        case LOOP:
                            cplx = eval_tree(expr);

                        }

                    return cplx;

                }
            }
        }
    }

    switch (how)    /* got here, so a mistake somewhere */
    {
        case SUMMATION:    mode = "Sum"; break;
        case PRODUCT:    mode = "Prod"; break;
        case LOOP:    mode = "every"; break;
        case VLOOP:    mode = "vevery"; break;
    }

    execerror("invalid usage of special function", mode);
}


Complex spec_sum(al)        /* do summation */
    ArgList *al;
{
    return iterate(al,SUMMATION);
}


Complex spec_prod(al)        /* do product */
    ArgList *al;
{
    return iterate(al,PRODUCT);
}


Complex spec_every(al)        /* do loop */
    ArgList *al;
{
    return iterate(al,LOOP);
}

Complex spec_vevery(al)        /* do verbose loop */
    ArgList *al;
{
    return iterate(al,VLOOP);
}


/*
*    multi() is a special function that takes any number of expressions
*    as arguments and evaluates them from left to right. It was added
*    to make certain operations possible from user-functions.
*/
Complex spec_multi(al)
    ArgList *al;
{
    while (al)    /* uses recursion to step through expressions */
    {
        (void)spec_multi(al->next);
        return eval_tree(al->node);
    }
}


static Complex spec_extreme(al,cmp,what)    /* maximum of Re(arg) in arg-list */
    ArgList *al;
    double (*cmp)();
    char *what;        /* ascii string containing name of op */
{
    Complex mval, tval;

    if (al)        /* called with arguments */
    {
        mval = eval_tree(al->node);
        mval.imag = 0.0;

        al = al->next;

        while (al)
        {
            tval = eval_tree(al->node);
            mval.real = cmp(mval.real, tval.real);
            al = al->next;
        }

        return mval;
    }

    execerror("invalid usage of special function", what);
}

static double fnmax(a, b)
    double a, b;
{ return max(a,b); }

Complex spec_max(al)        /* return max of Re(arg) */
    ArgList *al;
{ return spec_extreme(al, fnmax, "max"); }


static double fnmin(a, b)
    double a, b;
{ return min(a,b); }

Complex spec_min(al)        /* return min of Re(arg) */
    ArgList *al;
{ return spec_extreme(al, fnmin, "min"); }