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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [sf_sine.c] - Rev 214
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/* @(#)z_sinef.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. ******************************************************************/ /****************************************************************** * sine generator * * Input: * x - floating point value * cosine - indicates cosine value * * Output: * Sine of x. * * Description: * This routine calculates sines and cosines. * *****************************************************************/ #include "fdlibm.h" #include "zmath.h" static const float HALF_PI = 1.570796326; static const float ONE_OVER_PI = 0.318309886; static const float r[] = { -0.1666665668, 0.8333025139e-02, -0.1980741872e-03, 0.2601903036e-5 }; float _DEFUN (sinef, (float, int), float x _AND int cosine) { int sgn, N; float y, XN, g, R, res; float YMAX = 210828714.0; switch (numtestf (x)) { case NAN: errno = EDOM; return (x); case INF: errno = EDOM; return (z_notanum_f.f); } /* Use sin and cos properties to ease computations. */ if (cosine) { sgn = 1; y = fabsf (x) + HALF_PI; } else { if (x < 0.0) { sgn = -1; y = -x; } else { sgn = 1; y = x; } } /* Check for values of y that will overflow here. */ if (y > YMAX) { errno = ERANGE; return (x); } /* Calculate the exponent. */ if (y < 0.0) N = (int) (y * ONE_OVER_PI - 0.5); else N = (int) (y * ONE_OVER_PI + 0.5); XN = (float) N; if (N & 1) sgn = -sgn; if (cosine) XN -= 0.5; y = fabsf (x) - XN * __PI; if (-z_rooteps_f < y && y < z_rooteps_f) res = y; else { g = y * y; /* Calculate the Taylor series. */ R = (((r[3] * g + r[2]) * g + r[1]) * g + r[0]) * g; /* Finally, compute the result. */ res = y + y * R; } res *= sgn; return (res); }
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