diff options
author | PikalaxALT <pikalaxalt@gmail.com> | 2017-12-15 09:38:53 -0500 |
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committer | PikalaxALT <pikalaxalt@gmail.com> | 2017-12-15 09:39:34 -0500 |
commit | f95a4a932476be2ba99e2fd081e8d2bc6ea12813 (patch) | |
tree | 75f67192cb2d7b7b575c94edda318e475239b63c /newlib/libm/mathfp/sf_exp.c | |
parent | f60aca96985e68c7d8a52eb7bc955fb80e132f73 (diff) |
Import newlib and create makefile
Diffstat (limited to 'newlib/libm/mathfp/sf_exp.c')
-rw-r--r-- | newlib/libm/mathfp/sf_exp.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/newlib/libm/mathfp/sf_exp.c b/newlib/libm/mathfp/sf_exp.c new file mode 100644 index 0000000..45d9c31 --- /dev/null +++ b/newlib/libm/mathfp/sf_exp.c @@ -0,0 +1,92 @@ + +/* @(#)z_expf.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. + ******************************************************************/ +/****************************************************************** + * Exponential Function + * + * Input: + * x - floating point value + * + * Output: + * e raised to x. + * + * Description: + * This routine returns e raised to the xth power. + * + *****************************************************************/ + +#include <float.h> +#include "fdlibm.h" +#include "zmath.h" + +static const float INV_LN2 = 1.442695040; +static const float LN2 = 0.693147180; +static const float p[] = { 0.249999999950, 0.00416028863 }; +static const float q[] = { 0.5, 0.04998717878 }; + +float +_DEFUN (expf, (float), + float x) +{ + int N; + float g, z, R, P, Q; + + switch (numtestf (x)) + { + case NAN: + errno = EDOM; + return (x); + case INF: + errno = ERANGE; + if (isposf (x)) + return (z_infinity_f.f); + else + return (0.0); + case 0: + return (1.0); + } + + /* Check for out of bounds. */ + if (x > BIGX || x < SMALLX) + { + errno = ERANGE; + return (x); + } + + /* Check for a value too small to calculate. */ + if (-z_rooteps_f < x && x < z_rooteps_f) + { + return (1.0); + } + + /* Calculate the exponent. */ + if (x < 0.0) + N = (int) (x * INV_LN2 - 0.5); + else + N = (int) (x * INV_LN2 + 0.5); + + /* Construct the mantissa. */ + g = x - N * LN2; + z = g * g; + P = g * (p[1] * z + p[0]); + Q = q[1] * z + q[0]; + R = 0.5 + P / (Q - P); + + /* Return the floating point value. */ + N++; + return (ldexpf (R, N)); +} + +#ifdef _DOUBLE_IS_32_BITS + +double exp (double x) +{ + return (double) expf ((float) x); +} + +#endif /* _DOUBLE_IS_32_BITS */ |