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complex divide: match C99 implementation

R=iant, ken2, r, r2, ken3
CC=golang-dev
https://golang.org/cl/1686044
This commit is contained in:
Russ Cox 2010-06-18 15:46:00 -07:00
parent 99b23a1e5b
commit 21ff75bc0e
7 changed files with 2569 additions and 41 deletions

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@ -4,33 +4,57 @@
#include "runtime.h"
// complex128div(num, den complex128) (quo complex128)
typedef struct Complex128 Complex128;
void
·complex128div(float64 numreal, float64 numimag,
float64 denreal, float64 denimag,
float64 quoreal, float64 quoimag)
·complex128div(Complex128 n, Complex128 d, Complex128 q)
{
int32 ninf, dinf, nnan, dnan;
float64 a, b, ratio, denom;
a = denreal;
if(a < 0)
a = -a;
b = denimag;
if(b < 0)
b = -b;
if(a <= b) {
if(b == 0)
panicstring("complex divide by zero");
ratio = denreal/denimag;
denom = denreal*ratio + denimag;
quoreal = (numreal*ratio + numimag) / denom;
quoimag = (numimag*ratio - numreal) / denom;
// Special cases as in C99.
ninf = isInf(n.real, 0) || isInf(n.imag, 0);
dinf = isInf(d.real, 0) || isInf(d.imag, 0);
nnan = !ninf && (isNaN(n.real) || isNaN(n.imag));
dnan = !dinf && (isNaN(d.real) || isNaN(d.imag));
if(nnan || dnan) {
q.real = NaN();
q.imag = NaN();
} else if(ninf && !dinf && !dnan) {
q.real = Inf(0);
q.imag = Inf(0);
} else if(!ninf && !nnan && dinf) {
q.real = 0;
q.imag = 0;
} else if(d.real == 0 && d.imag == 0) {
if(n.real == 0 && n.imag == 0) {
q.real = NaN();
q.imag = NaN();
} else {
q.real = Inf(0);
q.imag = Inf(0);
}
} else {
ratio = denimag/denreal;
denom = denimag*ratio + denreal;
quoreal = (numimag*ratio + numreal) / denom;
quoimag = (numimag - numreal*ratio) / denom;
// Standard complex arithmetic, factored to avoid unnecessary overflow.
a = d.real;
if(a < 0)
a = -a;
b = d.imag;
if(b < 0)
b = -b;
if(a <= b) {
ratio = d.real/d.imag;
denom = d.real*ratio + d.imag;
q.real = (n.real*ratio + n.imag) / denom;
q.imag = (n.imag*ratio - n.real) / denom;
} else {
ratio = d.imag/d.real;
denom = d.imag*ratio + d.real;
q.real = (n.imag*ratio + n.real) / denom;
q.imag = (n.imag - n.real*ratio) / denom;
}
}
FLUSH(&quoreal);
FLUSH(&quoimag);
FLUSH(&q);
}

61
test/cmplxdivide.c Normal file
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@ -0,0 +1,61 @@
// 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
main(void)
{
int i, j, k, l;
double complex n, d, q;
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;
printf("\tTest{cmplx(%s, %s), cmplx(%s, %s), cmplx(%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;
}

43
test/cmplxdivide.go Normal file
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@ -0,0 +1,43 @@
// $G $D/$F.go $D/cmplxdivide1.go && $L $D/$F.$A && ./$A.out
// 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.
// Driver for complex division table defined in cmplxdivide1.go
package main
import (
"cmath"
"fmt"
"math"
)
type Test struct{
f, g complex128
out complex128
}
var nan = math.NaN()
var inf = math.Inf(1)
var negzero = math.Copysign(0, -1)
func calike(a, b complex128) bool {
switch {
case cmath.IsInf(a) && cmath.IsInf(b):
return true
case cmath.IsNaN(a) && cmath.IsNaN(b):
return true
}
return a == b
}
func main() {
for _, t := range tests {
x := t.f/t.g
if !calike(x, t.out) {
fmt.Printf("%v/%v: expected %v error; got %v\n", t.f, t.g, t.out, x)
}
}
}

2406
test/cmplxdivide1.go Normal file

File diff suppressed because it is too large Load Diff

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@ -53,14 +53,6 @@ FAIL
=========== ./turing.go
Hello World!
=========== ./zerodivide.go
complex 0/0: expected no error; got "runtime error: complex divide by zero"
complex64 0/0: expected no error; got "runtime error: complex divide by zero"
complex128 0/0: expected no error; got "runtime error: complex divide by zero"
complex 1/0: expected no error; got "runtime error: complex divide by zero"
complex64 1/0: expected no error; got "runtime error: complex divide by zero"
complex128 1/0: expected no error; got "runtime error: complex divide by zero"
== ken/
=========== ken/cplx0.go

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@ -81,11 +81,11 @@ func test6() {
}
func test7() {
if syscall.ARCH == "arm" {
// ARM doesn't have floating point yet
if syscall.ARCH == "arm" || syscall.OS == "nacl" {
// ARM doesn't have integer divide trap yet
return
}
defer mustRecover("complex divide by zero")
var x, y complex
defer mustRecover("divide by zero")
var x, y int
println(x / y)
}

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@ -114,16 +114,15 @@ func error(fn func()) (error string) {
}
type FloatTest struct{
name string
f, g float64
out float64
}
var floatTests = []FloatTest{
FloatTest{"float64 0/0", 0, 0, nan },
FloatTest{"float64 nan/0", nan, 0, nan },
FloatTest{"float64 inf/0", inf, 0, inf },
FloatTest{"float64 -inf/0", negInf, 0, negInf },
FloatTest{0, 0, nan},
FloatTest{nan, 0, nan},
FloatTest{inf, 0, inf},
FloatTest{negInf, 0, negInf},
}
func alike(a, b float64) bool {
@ -138,6 +137,9 @@ func alike(a, b float64) bool {
func main() {
for _, t := range errorTests {
if t.err != "" && syscall.OS == "nacl" {
continue
}
err := error(t.fn)
switch {
case t.err == "" && err == "":
@ -158,7 +160,7 @@ func main() {
for _, t := range floatTests {
x := t.f/t.g
if !alike(x, t.out) {
fmt.Printf("%s: expected %g error; got %g\n", t.name, t.out, x)
fmt.Printf("%v/%v: expected %g error; got %g\n", t.f, t.g, t.out, x)
}
}
}