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all supplied erfc only valid for x > 0

This commit is contained in:
dwarning 2008-05-13 19:45:43 +00:00
parent bce499a9e1
commit 6c91a269ce
1 changed files with 19 additions and 19 deletions
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38
src/maths/misc/test_erfc.c
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@ -1,4 +1,4 @@
/* Paolo Nenzi 2002 - This program tests function
/* Paolo Nenzi 2002 - This program tests erfc function
* implementations.
* $Id$
*/
@ -9,29 +9,30 @@
*
* First we have the ierfc in spice, a sort of interpolation, which is
* fast to compute but gives is not so "good"
* Then we have derfc from cider, which is accurate but slow
* then we have glibc implementation.
* Then we have derfc from cider, which is accurate but slow, the code is from sedan's derfc.f .
* Both above are only valid for x > 0.0
* Then we have glibc/os specific implementation.
*
* Proposal:
*
* Use Linux implementation as defualt and then test cider one.
* Use glibc/os specific implementation as default and then test cider one.
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#ifdef HAVE_FPU_CTRL
#include <fpu_control.h>
#endif
double
derfc ( double x)
derfc(double x)
{
double sqrtPi, n, temp1, xSq, sum1, sum2;
sqrtPi = sqrt( M_PI );
x = fabs( x );
x = fabs( x ); /* only x > 0 interested */
n = 1.0;
xSq = 2.0 * x * x;
sum1 = 0.0;
@ -65,7 +66,6 @@ derfc ( double x)
double
ierfc(double x)
{
double t, z;
@ -84,23 +84,23 @@ ierfc(double x)
int main (void)
{
fpu_control_t prec;
double x = -100.0;
double x = -30.0;
double y1= 0.0, y2 = 0.0;
#if 0
#ifdef HAVE_FPU_CTRL
fpu_control_t prec;
_FPU_GETCW(prec);
prec &= ~_FPU_EXTENDED;
prec |= _FPU_DOUBLE;
_FPU_SETCW(prec);
#endif
for (;(x <= 100.0);)
{
y1 = ierfc(x);
y2 = derfc(x);
printf("A: %e \t s: %e \t c: %e \t (c-lin): %e\n", x, y1, y2, y2-erfc(x) );
x = x + 0.1;
}
for (;(x <= 30.0);)
{
y1 = ierfc(x);
y2 = derfc(x);
printf("x: %f \t ierfc: %e \t derfc: %e \t erfc: %e\n", x, y1, y2, erfc(x) );
x = x + 1.0;
}
exit(1);
}