diff options
Diffstat (limited to 'lib/msun/src/s_tanhf.c')
-rw-r--r-- | lib/msun/src/s_tanhf.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/msun/src/s_tanhf.c b/lib/msun/src/s_tanhf.c new file mode 100644 index 0000000..04f09c6 --- /dev/null +++ b/lib/msun/src/s_tanhf.c @@ -0,0 +1,55 @@ +/* s_tanhf.c -- float version of s_tanh.c. + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + */ + +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "math.h" +#include "math_private.h" + +static const float one=1.0, two=2.0, tiny = 1.0e-30, huge = 1.0e30; +float +tanhf(float x) +{ + float t,z; + int32_t jx,ix; + + GET_FLOAT_WORD(jx,x); + ix = jx&0x7fffffff; + + /* x is INF or NaN */ + if(ix>=0x7f800000) { + if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ + else return one/x-one; /* tanh(NaN) = NaN */ + } + + /* |x| < 9 */ + if (ix < 0x41100000) { /* |x|<9 */ + if (ix<0x39800000) { /* |x|<2**-12 */ + if(huge+x>one) return x; /* tanh(tiny) = tiny with inexact */ + } + if (ix>=0x3f800000) { /* |x|>=1 */ + t = expm1f(two*fabsf(x)); + z = one - two/(t+two); + } else { + t = expm1f(-two*fabsf(x)); + z= -t/(t+two); + } + /* |x| >= 9, return +-1 */ + } else { + z = one - tiny; /* raise inexact flag */ + } + return (jx>=0)? z: -z; +} |