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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [sf_asine.c] - Rev 859
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/* @(#)z_asinef.c 1.0 98/08/13 */ /****************************************************************** * The following routines are coded directly from the algorithms * and coefficients given in "Software Manual for the Elementary * Functions" by William J. Cody, Jr. and William Waite, Prentice * Hall, 1980. ******************************************************************/ /****************************************************************** * Arcsine * * Input: * x - floating point value * acosine - indicates acos calculation * * Output: * Arcsine of x. * * Description: * This routine calculates arcsine / arccosine. * *****************************************************************/ #include "fdlibm.h" #include "zmath.h" static const float p[] = { 0.933935835, -0.504400557 }; static const float q[] = { 0.560363004e+1, -0.554846723e+1 }; static const float a[] = { 0.0, 0.785398163 }; static const float b[] = { 1.570796326, 0.785398163 }; float _DEFUN (asinef, (float, int), float x _AND int acosine) { int flag, i; int branch = 0; float g, res, R, P, Q, y; /* Check for special values. */ i = numtestf (x); if (i == NAN || i == INF) { errno = EDOM; if (i == NAN) return (x); else return (z_infinity_f.f); } y = fabsf (x); flag = acosine; if (y > 0.5) { i = 1 - flag; /* Check for range error. */ if (y > 1.0) { errno = ERANGE; return (z_notanum_f.f); } g = (1 - y) / 2.0; y = -2 * sqrt (g); branch = 1; } else { i = flag; if (y < z_rooteps_f) res = y; else g = y * y; } if (y >= z_rooteps_f || branch == 1) { /* Calculate the Taylor series. */ P = (p[1] * g + p[0]) * g; Q = (g + q[1]) * g + q[0]; R = P / Q; res = y + y * R; } /* Calculate asine or acose. */ if (flag == 0) { res = (a[i] + res) + a[i]; if (x < 0.0) res = -res; } else { if (x < 0.0) res = (b[i] + res) + b[i]; else res = (a[i] - res) + a[i]; } return (res); }
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