root/test/cmplxdivide.c

DEFINITIONS

1. fmt
2. iscnan
3. main

// Copyright 2010 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// gcc '-std=c99' cmplxdivide.c && a.out >cmplxdivide1.go

#include <complex.h>
#include <math.h>
#include <stdio.h>
#include <string.h>

#define nelem(x) (sizeof(x)/sizeof((x)[0]))

double f[] = {
        0,
        1,
        -1,
        2,
        NAN,
        INFINITY,
        -INFINITY,
};

char*
fmt(double g)
{
        static char buf[10][30];
        static int n;
        char *p;
        
        p = buf[n++];
        if(n == 10)
                n = 0;
        sprintf(p, "%g", g);
        if(strcmp(p, "-0") == 0)
                strcpy(p, "negzero");
        return p;
}

int
iscnan(double complex d)
{
        return !isinf(creal(d)) && !isinf(cimag(d)) && (isnan(creal(d)) || isnan(cimag(d)));
}

double complex zero;    // attempt to hide zero division from gcc

int
main(void)
{
        int i, j, k, l;
        double complex n, d, q;
        
        printf("// skip\n");
        printf("// # generated by cmplxdivide.c\n");
        printf("\n");
        printf("package main\n");
        printf("var tests = []Test{\n");
        for(i=0; i<nelem(f); i++)
        for(j=0; j<nelem(f); j++)
        for(k=0; k<nelem(f); k++)
        for(l=0; l<nelem(f); l++) {
                n = f[i] + f[j]*I;
                d = f[k] + f[l]*I;
                q = n/d;
                
                // BUG FIX.
                // Gcc gets the wrong answer for NaN/0 unless both sides are NaN.
                // That is, it treats (NaN+NaN*I)/0 = NaN+NaN*I (a complex NaN)
                // but it then computes (1+NaN*I)/0 = Inf+NaN*I (a complex infinity).
                // Since both numerators are complex NaNs, it seems that the
                // results should agree in kind.  Override the gcc computation in this case.
                if(iscnan(n) && d == 0)
                        q = (NAN+NAN*I) / zero;

                printf("\tTest{complex(%s, %s), complex(%s, %s), complex(%s, %s)},\n",
                        fmt(creal(n)), fmt(cimag(n)),
                        fmt(creal(d)), fmt(cimag(d)),
                        fmt(creal(q)), fmt(cimag(q)));
        }
        printf("}\n");
        return 0;
}