micropython/lib/libm/acoshf.c
Damien George f04329e93b lib/libm: Add acosh, asinh, atanh, tan; get working with stmhal.
acoshf, asinhf, atanhf were added from musl.  mathsincos.c was
split up into its original, separate files (from newlibe-nano-2).
tan was added.

All of the important missing float functions are now implemented,
and pyboard now passes tests/float/math_fun.py (finally!).
2014-12-18 14:44:02 +00:00

33 lines
953 B
C

/*****************************************************************************/
/*****************************************************************************/
// acoshf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
#include "libm.h"
#if FLT_EVAL_METHOD==2
#undef sqrtf
#define sqrtf sqrtl
#elif FLT_EVAL_METHOD==1
#undef sqrtf
#define sqrtf sqrt
#endif
/* acosh(x) = log(x + sqrt(x*x-1)) */
float acoshf(float x)
{
union {float f; uint32_t i;} u = {x};
uint32_t a = u.i & 0x7fffffff;
if (a < 0x3f800000+(1<<23))
/* |x| < 2, invalid if x < 1 or nan */
/* up to 2ulp error in [1,1.125] */
return log1pf(x-1 + sqrtf((x-1)*(x-1)+2*(x-1)));
if (a < 0x3f800000+(12<<23))
/* |x| < 0x1p12 */
return logf(2*x - 1/(x+sqrtf(x*x-1)));
/* x >= 0x1p12 */
return logf(x) + 0.693147180559945309417232121458176568f;
}