| |
| /* @(#)z_sinehf.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. |
| ******************************************************************/ |
| /****************************************************************** |
| * Hyperbolic Sine |
| * |
| * Input: |
| * x - floating point value |
| * |
| * Output: |
| * hyperbolic sine of x |
| * |
| * Description: |
| * This routine calculates hyperbolic sines. |
| * |
| *****************************************************************/ |
| |
| #include <float.h> |
| #include "fdlibm.h" |
| #include "zmath.h" |
| |
| static const float q[] = { -0.428277109e+2 }; |
| static const float p[] = { -0.713793159e+1, |
| -0.190333399 }; |
| static const float LNV = 0.6931610107; |
| static const float INV_V2 = 0.2499930850; |
| static const float V_OVER2_MINUS1 = 0.1383027787e-4; |
| |
| float |
| _DEFUN (sinehf, (float, int), |
| float x _AND |
| int cosineh) |
| { |
| float y, f, P, Q, R, res, z, w; |
| int sgn = 1; |
| float WBAR = 18.55; |
| |
| /* Check for special values. */ |
| switch (numtestf (x)) |
| { |
| case NAN: |
| errno = EDOM; |
| return (x); |
| case INF: |
| errno = ERANGE; |
| return (ispos (x) ? z_infinity_f.f : -z_infinity_f.f); |
| } |
| |
| y = fabs (x); |
| |
| if (!cosineh && x < 0.0) |
| sgn = -1; |
| |
| if ((y > 1.0 && !cosineh) || cosineh) |
| { |
| if (y > BIGX) |
| { |
| w = y - LNV; |
| |
| /* Check for w > maximum here. */ |
| if (w > BIGX) |
| { |
| errno = ERANGE; |
| return (x); |
| } |
| |
| z = exp (w); |
| |
| if (w > WBAR) |
| res = z * (V_OVER2_MINUS1 + 1.0); |
| } |
| |
| else |
| { |
| z = exp (y); |
| if (cosineh) |
| res = (z + 1 / z) / 2.0; |
| else |
| res = (z - 1 / z) / 2.0; |
| } |
| |
| if (sgn < 0) |
| res = -res; |
| } |
| else |
| { |
| /* Check for y being too small. */ |
| if (y < z_rooteps_f) |
| { |
| res = x; |
| } |
| /* Calculate the Taylor series. */ |
| else |
| { |
| f = x * x; |
| Q = f + q[0]; |
| P = p[1] * f + p[0]; |
| R = f * (P / Q); |
| |
| res = x + x * R; |
| } |
| } |
| |
| return (res); |
| } |