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/* Test of tanh() function. ULP control.
$Id: tanh-02.c,v 1.1 2007/02/05 21:35:58 dmix Exp $
*/
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "progmem.h"
union lofl_u {
long lo;
float fl;
};
volatile union lofl_u v = { .lo = 1 };
PROGMEM const struct { /* Table of test cases. */
union lofl_u x; /* argument */
union lofl_u z; /* tanh(x) */
unsigned int maxulp; /* max possible error in ULP */
} t[] = {
{ { .fl= 0 }, { .fl= 0 }, 0 },
{ { 0x3a000000 }, { 0x39ffffff }, 1 },
{ { 0x3b000000 }, { 0x3affffeb }, 1 },
{ { 0x3e0ffffe }, { 0x3e0f0ee6 }, 4 },
{ { 0x3e0fffff }, { 0x3e0f0ee7 }, 4 },
{ { 0x3e100000 }, { 0x3e0f0ee8 }, 3 }, /* .140625 */
{ { 0x3e100001 }, { 0x3e0f0ee9 }, 3 },
{ { .fl= 0.25 }, { .fl= .24491866 }, 1 },
{ { .fl= 0.5 }, { .fl= .46211716 }, 1 },
{ { .fl= 1 }, { .fl= .76159416 }, 1 },
{ { .fl= 2 }, { .fl= .96402758 }, 1 },
{ { .fl= 5 }, { .fl= .99990920 }, 1 },
{ { .fl= 10 }, { .fl= 1.0 }, 0 },
};
void x_exit (int index)
{
#ifndef __AVR__
fprintf (stderr, "t[%d]: %#lx\n", index - 1, v.lo);
#endif
exit (index ? index : -1);
}
int main ()
{
union lofl_u x, z;
unsigned int maxulp;
unsigned long v1, z1, r;
int i;
for (i = 0; i < (int) (sizeof(t) / sizeof(t[0])); i++) {
x.lo = pgm_read_dword (& t[i].x);
z.lo = pgm_read_dword (& t[i].z);
maxulp = pgm_read_word (& t[i].maxulp);
v.fl = tanh (x.fl);
v1 = (v.lo < 0) ? (unsigned long)~(v.lo) : v.lo + 0x80000000;
z1 = (z.lo < 0) ? (unsigned long)~(z.lo) : z.lo + 0x80000000;
r = (v1 >= z1) ? v1 - z1 : z1 - v1;
if (r > maxulp) x_exit (i+1);
}
return 0;
}
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