diff options
author | Eric Andersen <andersen@codepoet.org> | 2001-05-10 00:40:28 +0000 |
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committer | Eric Andersen <andersen@codepoet.org> | 2001-05-10 00:40:28 +0000 |
commit | 1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch) | |
tree | 579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/double/asinh.c | |
parent | 22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff) |
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/double/asinh.c')
-rw-r--r-- | libm/double/asinh.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/libm/double/asinh.c b/libm/double/asinh.c new file mode 100644 index 000000000..57966d264 --- /dev/null +++ b/libm/double/asinh.c @@ -0,0 +1,165 @@ +/* asinh.c + * + * Inverse hyperbolic sine + * + * + * + * SYNOPSIS: + * + * double x, y, asinh(); + * + * y = asinh( x ); + * + * + * + * DESCRIPTION: + * + * Returns inverse hyperbolic sine of argument. + * + * If |x| < 0.5, the function is approximated by a rational + * form x + x**3 P(x)/Q(x). Otherwise, + * + * asinh(x) = log( x + sqrt(1 + x*x) ). + * + * + * + * ACCURACY: + * + * Relative error: + * arithmetic domain # trials peak rms + * DEC -3,3 75000 4.6e-17 1.1e-17 + * IEEE -1,1 30000 3.7e-16 7.8e-17 + * IEEE 1,3 30000 2.5e-16 6.7e-17 + * + */ + +/* asinh.c */ + +/* +Cephes Math Library Release 2.8: June, 2000 +Copyright 1984, 1995, 2000 by Stephen L. Moshier +*/ + + +#include <math.h> + +#ifdef UNK +static double P[] = { +-4.33231683752342103572E-3, +-5.91750212056387121207E-1, +-4.37390226194356683570E0, +-9.09030533308377316566E0, +-5.56682227230859640450E0 +}; +static double Q[] = { +/* 1.00000000000000000000E0,*/ + 1.28757002067426453537E1, + 4.86042483805291788324E1, + 6.95722521337257608734E1, + 3.34009336338516356383E1 +}; +#endif + +#ifdef DEC +static unsigned short P[] = { +0136215,0173033,0110410,0105475, +0140027,0076361,0020056,0164520, +0140613,0173401,0160136,0053142, +0141021,0070744,0000503,0176261, +0140662,0021550,0073106,0133351 +}; +static unsigned short Q[] = { +/* 0040200,0000000,0000000,0000000,*/ +0041116,0001336,0034120,0173054, +0041502,0065300,0013144,0021231, +0041613,0022376,0035516,0153063, +0041405,0115216,0054265,0004557 +}; +#endif + +#ifdef IBMPC +static unsigned short P[] = { +0x1168,0x7221,0xbec3,0xbf71, +0xdd2a,0x2405,0xef9e,0xbfe2, +0xcacc,0x3c0b,0x7ee0,0xc011, +0x7f96,0x8028,0x2e3c,0xc022, +0xd6dd,0x0ec8,0x446d,0xc016 +}; +static unsigned short Q[] = { +/* 0x0000,0x0000,0x0000,0x3ff0,*/ +0x1ec5,0xc70a,0xc05b,0x4029, +0x8453,0x02cc,0x4d58,0x4048, +0xdac6,0xc769,0x649f,0x4051, +0xa12e,0xcb16,0xb351,0x4040 +}; +#endif + +#ifdef MIEEE +static unsigned short P[] = { +0xbf71,0xbec3,0x7221,0x1168, +0xbfe2,0xef9e,0x2405,0xdd2a, +0xc011,0x7ee0,0x3c0b,0xcacc, +0xc022,0x2e3c,0x8028,0x7f96, +0xc016,0x446d,0x0ec8,0xd6dd +}; +static unsigned short Q[] = { +0x4029,0xc05b,0xc70a,0x1ec5, +0x4048,0x4d58,0x02cc,0x8453, +0x4051,0x649f,0xc769,0xdac6, +0x4040,0xb351,0xcb16,0xa12e +}; +#endif + +#ifdef ANSIPROT +extern double polevl ( double, void *, int ); +extern double p1evl ( double, void *, int ); +extern double sqrt ( double ); +extern double log ( double ); +#else +double log(), sqrt(), polevl(), p1evl(); +#endif +extern double LOGE2, INFINITY; + +double asinh(xx) +double xx; +{ +double a, z, x; +int sign; + +#ifdef MINUSZERO +if( xx == 0.0 ) + return(xx); +#endif +if( xx < 0.0 ) + { + sign = -1; + x = -xx; + } +else + { + sign = 1; + x = xx; + } + +if( x > 1.0e8 ) + { +#ifdef INFINITIES + if( x == INFINITY ) + return(xx); +#endif + return( sign * (log(x) + LOGE2) ); + } + +z = x * x; +if( x < 0.5 ) + { + a = ( polevl(z, P, 4)/p1evl(z, Q, 4) ) * z; + a = a * x + x; + if( sign < 0 ) + a = -a; + return(a); + } + +a = sqrt( z + 1.0 ); +return( sign * log(x + a) ); +} |