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/ldouble/gammal.c | |
parent | 22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff) |
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/ldouble/gammal.c')
-rw-r--r-- | libm/ldouble/gammal.c | 764 |
1 files changed, 764 insertions, 0 deletions
diff --git a/libm/ldouble/gammal.c b/libm/ldouble/gammal.c new file mode 100644 index 000000000..de7ed89a2 --- /dev/null +++ b/libm/ldouble/gammal.c @@ -0,0 +1,764 @@ +/* gammal.c + * + * Gamma function + * + * + * + * SYNOPSIS: + * + * long double x, y, gammal(); + * extern int sgngam; + * + * y = gammal( x ); + * + * + * + * DESCRIPTION: + * + * Returns gamma function of the argument. The result is + * correctly signed, and the sign (+1 or -1) is also + * returned in a global (extern) variable named sgngam. + * This variable is also filled in by the logarithmic gamma + * function lgam(). + * + * Arguments |x| <= 13 are reduced by recurrence and the function + * approximated by a rational function of degree 7/8 in the + * interval (2,3). Large arguments are handled by Stirling's + * formula. Large negative arguments are made positive using + * a reflection formula. + * + * + * ACCURACY: + * + * Relative error: + * arithmetic domain # trials peak rms + * IEEE -40,+40 10000 3.6e-19 7.9e-20 + * IEEE -1755,+1755 10000 4.8e-18 6.5e-19 + * + * Accuracy for large arguments is dominated by error in powl(). + * + */ +/* lgaml() + * + * Natural logarithm of gamma function + * + * + * + * SYNOPSIS: + * + * long double x, y, lgaml(); + * extern int sgngam; + * + * y = lgaml( x ); + * + * + * + * DESCRIPTION: + * + * Returns the base e (2.718...) logarithm of the absolute + * value of the gamma function of the argument. + * The sign (+1 or -1) of the gamma function is returned in a + * global (extern) variable named sgngam. + * + * For arguments greater than 33, the logarithm of the gamma + * function is approximated by the logarithmic version of + * Stirling's formula using a polynomial approximation of + * degree 4. Arguments between -33 and +33 are reduced by + * recurrence to the interval [2,3] of a rational approximation. + * The cosecant reflection formula is employed for arguments + * less than -33. + * + * Arguments greater than MAXLGML (10^4928) return MAXNUML. + * + * + * + * ACCURACY: + * + * + * arithmetic domain # trials peak rms + * IEEE -40, 40 100000 2.2e-19 4.6e-20 + * IEEE 10^-2000,10^+2000 20000 1.6e-19 3.3e-20 + * The error criterion was relative when the function magnitude + * was greater than one but absolute when it was less than one. + * + */ + +/* gamma.c */ +/* gamma function */ + +/* +Copyright 1994 by Stephen L. Moshier +*/ + + +#include <math.h> +/* +gamma(x+2) = gamma(x+2) P(x)/Q(x) +0 <= x <= 1 +Relative error +n=7, d=8 +Peak error = 1.83e-20 +Relative error spread = 8.4e-23 +*/ +#if UNK +static long double P[8] = { + 4.212760487471622013093E-5L, + 4.542931960608009155600E-4L, + 4.092666828394035500949E-3L, + 2.385363243461108252554E-2L, + 1.113062816019361559013E-1L, + 3.629515436640239168939E-1L, + 8.378004301573126728826E-1L, + 1.000000000000000000009E0L, +}; +static long double Q[9] = { +-1.397148517476170440917E-5L, + 2.346584059160635244282E-4L, +-1.237799246653152231188E-3L, +-7.955933682494738320586E-4L, + 2.773706565840072979165E-2L, +-4.633887671244534213831E-2L, +-2.243510905670329164562E-1L, + 4.150160950588455434583E-1L, + 9.999999999999999999908E-1L, +}; +#endif +#if IBMPC +static short P[] = { +0x434a,0x3f22,0x2bda,0xb0b2,0x3ff0, XPD +0xf5aa,0xe82f,0x335b,0xee2e,0x3ff3, XPD +0xbe6c,0x3757,0xc717,0x861b,0x3ff7, XPD +0x7f43,0x5196,0xb166,0xc368,0x3ff9, XPD +0x9549,0x8eb5,0x8c3a,0xe3f4,0x3ffb, XPD +0x8d75,0x23af,0xc8e4,0xb9d4,0x3ffd, XPD +0x29cf,0x19b3,0x16c8,0xd67a,0x3ffe, XPD +0x0000,0x0000,0x0000,0x8000,0x3fff, XPD +}; +static short Q[] = { +0x5473,0x2de8,0x1268,0xea67,0xbfee, XPD +0x334b,0xc2f0,0xa2dd,0xf60e,0x3ff2, XPD +0xbeed,0x1853,0xa691,0xa23d,0xbff5, XPD +0x296e,0x7cb1,0x5dfd,0xd08f,0xbff4, XPD +0x0417,0x7989,0xd7bc,0xe338,0x3ff9, XPD +0x3295,0x3698,0xd580,0xbdcd,0xbffa, XPD +0x75ef,0x3ab7,0x4ad3,0xe5bc,0xbffc, XPD +0xe458,0x2ec7,0xfd57,0xd47c,0x3ffd, XPD +0x0000,0x0000,0x0000,0x8000,0x3fff, XPD +}; +#endif +#if MIEEE +static long P[24] = { +0x3ff00000,0xb0b22bda,0x3f22434a, +0x3ff30000,0xee2e335b,0xe82ff5aa, +0x3ff70000,0x861bc717,0x3757be6c, +0x3ff90000,0xc368b166,0x51967f43, +0x3ffb0000,0xe3f48c3a,0x8eb59549, +0x3ffd0000,0xb9d4c8e4,0x23af8d75, +0x3ffe0000,0xd67a16c8,0x19b329cf, +0x3fff0000,0x80000000,0x00000000, +}; +static long Q[27] = { +0xbfee0000,0xea671268,0x2de85473, +0x3ff20000,0xf60ea2dd,0xc2f0334b, +0xbff50000,0xa23da691,0x1853beed, +0xbff40000,0xd08f5dfd,0x7cb1296e, +0x3ff90000,0xe338d7bc,0x79890417, +0xbffa0000,0xbdcdd580,0x36983295, +0xbffc0000,0xe5bc4ad3,0x3ab775ef, +0x3ffd0000,0xd47cfd57,0x2ec7e458, +0x3fff0000,0x80000000,0x00000000, +}; +#endif +/* +static long double P[] = { +-3.01525602666895735709e0L, +-3.25157411956062339893e1L, +-2.92929976820724030353e2L, +-1.70730828800510297666e3L, +-7.96667499622741999770e3L, +-2.59780216007146401957e4L, +-5.99650230220855581642e4L, +-7.15743521530849602425e4L +}; +static long double Q[] = { + 1.00000000000000000000e0L, +-1.67955233807178858919e1L, + 8.85946791747759881659e1L, + 5.69440799097468430177e1L, +-1.98526250512761318471e3L, + 3.31667508019495079814e3L, + 1.60577839621734713377e4L, +-2.97045081369399940529e4L, +-7.15743521530849602412e4L +}; +*/ +#define MAXGAML 1755.455L +/*static long double LOGPI = 1.14472988584940017414L;*/ + +/* Stirling's formula for the gamma function +gamma(x) = sqrt(2 pi) x^(x-.5) exp(-x) (1 + 1/x P(1/x)) +z(x) = x +13 <= x <= 1024 +Relative error +n=8, d=0 +Peak error = 9.44e-21 +Relative error spread = 8.8e-4 +*/ +#if UNK +static long double STIR[9] = { + 7.147391378143610789273E-4L, +-2.363848809501759061727E-5L, +-5.950237554056330156018E-4L, + 6.989332260623193171870E-5L, + 7.840334842744753003862E-4L, +-2.294719747873185405699E-4L, +-2.681327161876304418288E-3L, + 3.472222222230075327854E-3L, + 8.333333333333331800504E-2L, +}; +#endif +#if IBMPC +static short STIR[] = { +0x6ede,0x69f7,0x54e3,0xbb5d,0x3ff4, XPD +0xc395,0x0295,0x4443,0xc64b,0xbfef, XPD +0xba6f,0x7c59,0x5e47,0x9bfb,0xbff4, XPD +0x5704,0x1a39,0xb11d,0x9293,0x3ff1, XPD +0x30b7,0x1a21,0x98b2,0xcd87,0x3ff4, XPD +0xbef3,0x7023,0x6a08,0xf09e,0xbff2, XPD +0x3a1c,0x5ac8,0x3478,0xafb9,0xbff6, XPD +0xc3c9,0x906e,0x38e3,0xe38e,0x3ff6, XPD +0xa1d5,0xaaaa,0xaaaa,0xaaaa,0x3ffb, XPD +}; +#endif +#if MIEEE +static long STIR[27] = { +0x3ff40000,0xbb5d54e3,0x69f76ede, +0xbfef0000,0xc64b4443,0x0295c395, +0xbff40000,0x9bfb5e47,0x7c59ba6f, +0x3ff10000,0x9293b11d,0x1a395704, +0x3ff40000,0xcd8798b2,0x1a2130b7, +0xbff20000,0xf09e6a08,0x7023bef3, +0xbff60000,0xafb93478,0x5ac83a1c, +0x3ff60000,0xe38e38e3,0x906ec3c9, +0x3ffb0000,0xaaaaaaaa,0xaaaaa1d5, +}; +#endif +#define MAXSTIR 1024.0L +static long double SQTPI = 2.50662827463100050242E0L; + +/* 1/gamma(x) = z P(z) + * z(x) = 1/x + * 0 < x < 0.03125 + * Peak relative error 4.2e-23 + */ +#if UNK +static long double S[9] = { +-1.193945051381510095614E-3L, + 7.220599478036909672331E-3L, +-9.622023360406271645744E-3L, +-4.219773360705915470089E-2L, + 1.665386113720805206758E-1L, +-4.200263503403344054473E-2L, +-6.558780715202540684668E-1L, + 5.772156649015328608253E-1L, + 1.000000000000000000000E0L, +}; +#endif +#if IBMPC +static short S[] = { +0xbaeb,0xd6d3,0x25e5,0x9c7e,0xbff5, XPD +0xfe9a,0xceb4,0xc74e,0xec9a,0x3ff7, XPD +0x9225,0xdfef,0xb0e9,0x9da5,0xbff8, XPD +0x10b0,0xec17,0x87dc,0xacd7,0xbffa, XPD +0x6b8d,0x7515,0x1905,0xaa89,0x3ffc, XPD +0xf183,0x126b,0xf47d,0xac0a,0xbffa, XPD +0x7bf6,0x57d1,0xa013,0xa7e7,0xbffe, XPD +0xc7a9,0x7db0,0x67e3,0x93c4,0x3ffe, XPD +0x0000,0x0000,0x0000,0x8000,0x3fff, XPD +}; +#endif +#if MIEEE +static long S[27] = { +0xbff50000,0x9c7e25e5,0xd6d3baeb, +0x3ff70000,0xec9ac74e,0xceb4fe9a, +0xbff80000,0x9da5b0e9,0xdfef9225, +0xbffa0000,0xacd787dc,0xec1710b0, +0x3ffc0000,0xaa891905,0x75156b8d, +0xbffa0000,0xac0af47d,0x126bf183, +0xbffe0000,0xa7e7a013,0x57d17bf6, +0x3ffe0000,0x93c467e3,0x7db0c7a9, +0x3fff0000,0x80000000,0x00000000, +}; +#endif +/* 1/gamma(-x) = z P(z) + * z(x) = 1/x + * 0 < x < 0.03125 + * Peak relative error 5.16e-23 + * Relative error spread = 2.5e-24 + */ +#if UNK +static long double SN[9] = { + 1.133374167243894382010E-3L, + 7.220837261893170325704E-3L, + 9.621911155035976733706E-3L, +-4.219773343731191721664E-2L, +-1.665386113944413519335E-1L, +-4.200263503402112910504E-2L, + 6.558780715202536547116E-1L, + 5.772156649015328608727E-1L, +-1.000000000000000000000E0L, +}; +#endif +#if IBMPC +static short SN[] = { +0x5dd1,0x02de,0xb9f7,0x948d,0x3ff5, XPD +0x989b,0xdd68,0xc5f1,0xec9c,0x3ff7, XPD +0x2ca1,0x18f0,0x386f,0x9da5,0x3ff8, XPD +0x783f,0x41dd,0x87d1,0xacd7,0xbffa, XPD +0x7a5b,0xd76d,0x1905,0xaa89,0xbffc, XPD +0x7f64,0x1234,0xf47d,0xac0a,0xbffa, XPD +0x5e26,0x57d1,0xa013,0xa7e7,0x3ffe, XPD +0xc7aa,0x7db0,0x67e3,0x93c4,0x3ffe, XPD +0x0000,0x0000,0x0000,0x8000,0xbfff, XPD +}; +#endif +#if MIEEE +static long SN[27] = { +0x3ff50000,0x948db9f7,0x02de5dd1, +0x3ff70000,0xec9cc5f1,0xdd68989b, +0x3ff80000,0x9da5386f,0x18f02ca1, +0xbffa0000,0xacd787d1,0x41dd783f, +0xbffc0000,0xaa891905,0xd76d7a5b, +0xbffa0000,0xac0af47d,0x12347f64, +0x3ffe0000,0xa7e7a013,0x57d15e26, +0x3ffe0000,0x93c467e3,0x7db0c7aa, +0xbfff0000,0x80000000,0x00000000, +}; +#endif + +int sgngaml = 0; +extern int sgngaml; +extern long double MAXLOGL, MAXNUML, PIL; +/* #define PIL 3.14159265358979323846L */ +/* #define MAXNUML 1.189731495357231765021263853E4932L */ + +#ifdef ANSIPROT +extern long double fabsl ( long double ); +extern long double lgaml ( long double ); +extern long double logl ( long double ); +extern long double expl ( long double ); +extern long double gammal ( long double ); +extern long double sinl ( long double ); +extern long double floorl ( long double ); +extern long double powl ( long double, long double ); +extern long double polevll ( long double, void *, int ); +extern long double p1evll ( long double, void *, int ); +extern int isnanl ( long double ); +extern int isfinitel ( long double ); +static long double stirf ( long double ); +#else +long double fabsl(), lgaml(), logl(), expl(), gammal(), sinl(); +long double floorl(), powl(), polevll(), p1evll(), isnanl(), isfinitel(); +static long double stirf(); +#endif +#ifdef INFINITIES +extern long double INFINITYL; +#endif +#ifdef NANS +extern long double NANL; +#endif + +/* Gamma function computed by Stirling's formula. + */ +static long double stirf(x) +long double x; +{ +long double y, w, v; + +w = 1.0L/x; +/* For large x, use rational coefficients from the analytical expansion. */ +if( x > 1024.0L ) + w = (((((6.97281375836585777429E-5L * w + + 7.84039221720066627474E-4L) * w + - 2.29472093621399176955E-4L) * w + - 2.68132716049382716049E-3L) * w + + 3.47222222222222222222E-3L) * w + + 8.33333333333333333333E-2L) * w + + 1.0L; +else + w = 1.0L + w * polevll( w, STIR, 8 ); +y = expl(x); +if( x > MAXSTIR ) + { /* Avoid overflow in pow() */ + v = powl( x, 0.5L * x - 0.25L ); + y = v * (v / y); + } +else + { + y = powl( x, x - 0.5L ) / y; + } +y = SQTPI * y * w; +return( y ); +} + + + +long double gammal(x) +long double x; +{ +long double p, q, z; +int i; + +sgngaml = 1; +#ifdef NANS +if( isnanl(x) ) + return(NANL); +#endif +#ifdef INFINITIES +if(x == INFINITYL) + return(INFINITYL); +#ifdef NANS +if(x == -INFINITYL) + goto gamnan; +#endif +#endif +q = fabsl(x); + +if( q > 13.0L ) + { + if( q > MAXGAML ) + goto goverf; + if( x < 0.0L ) + { + p = floorl(q); + if( p == q ) + { +gamnan: +#ifdef NANS + mtherr( "gammal", DOMAIN ); + return (NANL); +#else + goto goverf; +#endif + } + i = p; + if( (i & 1) == 0 ) + sgngaml = -1; + z = q - p; + if( z > 0.5L ) + { + p += 1.0L; + z = q - p; + } + z = q * sinl( PIL * z ); + z = fabsl(z) * stirf(q); + if( z <= PIL/MAXNUML ) + { +goverf: +#ifdef INFINITIES + return( sgngaml * INFINITYL); +#else + mtherr( "gammal", OVERFLOW ); + return( sgngaml * MAXNUML); +#endif + } + z = PIL/z; + } + else + { + z = stirf(x); + } + return( sgngaml * z ); + } + +z = 1.0L; +while( x >= 3.0L ) + { + x -= 1.0L; + z *= x; + } + +while( x < -0.03125L ) + { + z /= x; + x += 1.0L; + } + +if( x <= 0.03125L ) + goto small; + +while( x < 2.0L ) + { + z /= x; + x += 1.0L; + } + +if( x == 2.0L ) + return(z); + +x -= 2.0L; +p = polevll( x, P, 7 ); +q = polevll( x, Q, 8 ); +return( z * p / q ); + +small: +if( x == 0.0L ) + { + goto gamnan; + } +else + { + if( x < 0.0L ) + { + x = -x; + q = z / (x * polevll( x, SN, 8 )); + } + else + q = z / (x * polevll( x, S, 8 )); + } +return q; +} + + + +/* A[]: Stirling's formula expansion of log gamma + * B[], C[]: log gamma function between 2 and 3 + */ + + +/* log gamma(x) = ( x - 0.5 ) * log(x) - x + LS2PI + 1/x A(1/x^2) + * x >= 8 + * Peak relative error 1.51e-21 + * Relative spread of error peaks 5.67e-21 + */ +#if UNK +static long double A[7] = { + 4.885026142432270781165E-3L, +-1.880801938119376907179E-3L, + 8.412723297322498080632E-4L, +-5.952345851765688514613E-4L, + 7.936507795855070755671E-4L, +-2.777777777750349603440E-3L, + 8.333333333333331447505E-2L, +}; +#endif +#if IBMPC +static short A[] = { +0xd984,0xcc08,0x91c2,0xa012,0x3ff7, XPD +0x3d91,0x0304,0x3da1,0xf685,0xbff5, XPD +0x3bdc,0xaad1,0xd492,0xdc88,0x3ff4, XPD +0x8b20,0x9fce,0x844e,0x9c09,0xbff4, XPD +0xf8f2,0x30e5,0x0092,0xd00d,0x3ff4, XPD +0x4d88,0x03a8,0x60b6,0xb60b,0xbff6, XPD +0x9fcc,0xaaaa,0xaaaa,0xaaaa,0x3ffb, XPD +}; +#endif +#if MIEEE +static long A[21] = { +0x3ff70000,0xa01291c2,0xcc08d984, +0xbff50000,0xf6853da1,0x03043d91, +0x3ff40000,0xdc88d492,0xaad13bdc, +0xbff40000,0x9c09844e,0x9fce8b20, +0x3ff40000,0xd00d0092,0x30e5f8f2, +0xbff60000,0xb60b60b6,0x03a84d88, +0x3ffb0000,0xaaaaaaaa,0xaaaa9fcc, +}; +#endif + +/* log gamma(x+2) = x B(x)/C(x) + * 0 <= x <= 1 + * Peak relative error 7.16e-22 + * Relative spread of error peaks 4.78e-20 + */ +#if UNK +static long double B[7] = { +-2.163690827643812857640E3L, +-8.723871522843511459790E4L, +-1.104326814691464261197E6L, +-6.111225012005214299996E6L, +-1.625568062543700591014E7L, +-2.003937418103815175475E7L, +-8.875666783650703802159E6L, +}; +static long double C[7] = { +/* 1.000000000000000000000E0L,*/ +-5.139481484435370143617E2L, +-3.403570840534304670537E4L, +-6.227441164066219501697E5L, +-4.814940379411882186630E6L, +-1.785433287045078156959E7L, +-3.138646407656182662088E7L, +-2.099336717757895876142E7L, +}; +#endif +#if IBMPC +static short B[] = { +0x9557,0x4995,0x0da1,0x873b,0xc00a, XPD +0xfe44,0x9af8,0x5b8c,0xaa63,0xc00f, XPD +0x5aa8,0x7cf5,0x3684,0x86ce,0xc013, XPD +0x259a,0x258c,0xf206,0xba7f,0xc015, XPD +0xbe18,0x1ca3,0xc0a0,0xf80a,0xc016, XPD +0x168f,0x2c42,0x6717,0x98e3,0xc017, XPD +0x2051,0x9d55,0x92c8,0x876e,0xc016, XPD +}; +static short C[] = { +/*0x0000,0x0000,0x0000,0x8000,0x3fff, XPD*/ +0xaa77,0xcf2f,0xae76,0x807c,0xc008, XPD +0xb280,0x0d74,0xb55a,0x84f3,0xc00e, XPD +0xa505,0xcd30,0x81dc,0x9809,0xc012, XPD +0x3369,0x4246,0xb8c2,0x92f0,0xc015, XPD +0x63cf,0x6aee,0xbe6f,0x8837,0xc017, XPD +0x26bb,0xccc7,0xb009,0xef75,0xc017, XPD +0x462b,0xbae8,0xab96,0xa02a,0xc017, XPD +}; +#endif +#if MIEEE +static long B[21] = { +0xc00a0000,0x873b0da1,0x49959557, +0xc00f0000,0xaa635b8c,0x9af8fe44, +0xc0130000,0x86ce3684,0x7cf55aa8, +0xc0150000,0xba7ff206,0x258c259a, +0xc0160000,0xf80ac0a0,0x1ca3be18, +0xc0170000,0x98e36717,0x2c42168f, +0xc0160000,0x876e92c8,0x9d552051, +}; +static long C[21] = { +/*0x3fff0000,0x80000000,0x00000000,*/ +0xc0080000,0x807cae76,0xcf2faa77, +0xc00e0000,0x84f3b55a,0x0d74b280, +0xc0120000,0x980981dc,0xcd30a505, +0xc0150000,0x92f0b8c2,0x42463369, +0xc0170000,0x8837be6f,0x6aee63cf, +0xc0170000,0xef75b009,0xccc726bb, +0xc0170000,0xa02aab96,0xbae8462b, +}; +#endif + +/* log( sqrt( 2*pi ) ) */ +static long double LS2PI = 0.91893853320467274178L; +#define MAXLGM 1.04848146839019521116e+4928L + + +/* Logarithm of gamma function */ + + +long double lgaml(x) +long double x; +{ +long double p, q, w, z, f, nx; +int i; + +sgngaml = 1; +#ifdef NANS +if( isnanl(x) ) + return(NANL); +#endif +#ifdef INFINITIES +if( !isfinitel(x) ) + return(INFINITYL); +#endif +if( x < -34.0L ) + { + q = -x; + w = lgaml(q); /* note this modifies sgngam! */ + p = floorl(q); + if( p == q ) + { +#ifdef INFINITIES + mtherr( "lgaml", SING ); + return (INFINITYL); +#else + goto loverf; +#endif + } + i = p; + if( (i & 1) == 0 ) + sgngaml = -1; + else + sgngaml = 1; + z = q - p; + if( z > 0.5L ) + { + p += 1.0L; + z = p - q; + } + z = q * sinl( PIL * z ); + if( z == 0.0L ) + goto loverf; +/* z = LOGPI - logl( z ) - w; */ + z = logl( PIL/z ) - w; + return( z ); + } + +if( x < 13.0L ) + { + z = 1.0L; + nx = floorl( x + 0.5L ); + f = x - nx; + while( x >= 3.0L ) + { + nx -= 1.0L; + x = nx + f; + z *= x; + } + while( x < 2.0L ) + { + if( fabsl(x) <= 0.03125 ) + goto lsmall; + z /= nx + f; + nx += 1.0L; + x = nx + f; + } + if( z < 0.0L ) + { + sgngaml = -1; + z = -z; + } + else + sgngaml = 1; + if( x == 2.0L ) + return( logl(z) ); + x = (nx - 2.0L) + f; + p = x * polevll( x, B, 6 ) / p1evll( x, C, 7); + return( logl(z) + p ); + } + +if( x > MAXLGM ) + { +loverf: +#ifdef INFINITIES + return( sgngaml * INFINITYL ); +#else + mtherr( "lgaml", OVERFLOW ); + return( sgngaml * MAXNUML ); +#endif + } + +q = ( x - 0.5L ) * logl(x) - x + LS2PI; +if( x > 1.0e10L ) + return(q); +p = 1.0L/(x*x); +q += polevll( p, A, 6 ) / x; +return( q ); + + +lsmall: +if( x == 0.0L ) + goto loverf; +if( x < 0.0L ) + { + x = -x; + q = z / (x * polevll( x, SN, 8 )); + } +else + q = z / (x * polevll( x, S, 8 )); +if( q < 0.0L ) + { + sgngaml = -1; + q = -q; + } +else + sgngaml = 1; +q = logl( q ); +return(q); +} |