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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [mathfp/] [s_asine.c] - Rev 301
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/* @(#)z_asine.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. ******************************************************************/ /* FUNCTION <<asin>>, <<asinf>>, <<acos>>, <<acosf>>, <<asine>>, <<asinef>>---arc sine or cosine INDEX asin INDEX asinf INDEX acos INDEX acosf INDEX asine INDEX asinef ANSI_SYNOPSIS #include <math.h> double asine(double <[x]>); float asinef(float <[x]>); double asin(double <[x]>); float asinf(float <[x]>); double acos(double <[x]>); float acosf(float <[x]>); TRAD_SYNOPSIS #include <math.h> double asine(<[x]>); double <[x]>; float asinef(<[x]>); float <[x]>; double asin(<[x]>) double <[x]>; float asinf(<[x]>) float <[x]>; double acos(<[x]>) double <[x]>; float acosf(<[x]>) float <[x]>; DESCRIPTION <<asin>> computes the inverse sine or cosine of the argument <[x]>. Arguments to <<asin>> and <<acos>> must be in the range @minus{}1 to 1. <<asinf>> and <<acosf>> are identical to <<asin>> and <<acos>>, other than taking and returning floats. RETURNS @ifnottex <<asin>> and <<acos>> return values in radians, in the range of -pi/2 to pi/2. @end ifnottex @tex <<asin>> and <<acos>> return values in radians, in the range of $-\pi/2$ to $\pi/2$. @end tex If <[x]> is not in the range @minus{}1 to 1, <<asin>> and <<asinf>> return NaN (not a number), set the global variable <<errno>> to <<EDOM>>, and issue a <<DOMAIN error>> message. */ /****************************************************************** * 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" #ifndef _DOUBLE_IS_32BITS static const double p[] = { -0.27368494524164255994e+2, 0.57208227877891731407e+2, -0.39688862997404877339e+2, 0.10152522233806463645e+2, -0.69674573447350646411 }; static const double q[] = { -0.16421096714498560795e+3, 0.41714430248260412556e+3, -0.38186303361750149284e+3, 0.15095270841030604719e+3, -0.23823859153670238830e+2 }; static const double a[] = { 0.0, 0.78539816339744830962 }; static const double b[] = { 1.57079632679489661923, 0.78539816339744830962 }; double _DEFUN (asine, (double, int), double x _AND int acosine) { int flag, i; int branch = 0; double g, res, R, P, Q, y; /* Check for special values. */ i = numtest (x); if (i == NAN || i == INF) { errno = EDOM; if (i == NAN) return (x); else return (z_infinity.d); } y = fabs (x); flag = acosine; if (y > 0.5) { i = 1 - flag; /* Check for range error. */ if (y > 1.0) { errno = ERANGE; return (z_notanum.d); } g = (1 - y) / 2.0; y = -2 * sqrt (g); branch = 1; } else { i = flag; if (y < z_rooteps) res = y; else g = y * y; } if (y >= z_rooteps || branch == 1) { /* Calculate the Taylor series. */ P = ((((p[4] * g + p[3]) * g + p[2]) * g + p[1]) * g + p[0]) * g; Q = ((((g + q[4]) * g + q[3]) * g + q[2]) * 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); } #endif /* _DOUBLE_IS_32BITS */
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