diff options
Diffstat (limited to 'lib/msun/src/s_erf.c')
-rw-r--r-- | lib/msun/src/s_erf.c | 62 |
1 files changed, 35 insertions, 27 deletions
diff --git a/lib/msun/src/s_erf.c b/lib/msun/src/s_erf.c index 854767b..e1d63bc 100644 --- a/lib/msun/src/s_erf.c +++ b/lib/msun/src/s_erf.c @@ -111,18 +111,25 @@ __FBSDID("$FreeBSD$"); #include "math.h" #include "math_private.h" +/* XXX Prevent compilers from erroneously constant folding: */ +static const volatile double tiny= 1e-300; + static const double -tiny = 1e-300, -half= 5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */ -one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */ -two = 2.00000000000000000000e+00, /* 0x40000000, 0x00000000 */ - /* c = (float)0.84506291151 */ +half= 0.5, +one = 1, +two = 2, +/* c = (float)0.84506291151 */ erx = 8.45062911510467529297e-01, /* 0x3FEB0AC1, 0x60000000 */ /* - * Coefficients for approximation to erf on [0,0.84375] + * In the domain [0, 2**-28], only the first term in the power series + * expansion of erf(x) is used. The magnitude of the first neglected + * terms is less than 2**-84. */ efx = 1.28379167095512586316e-01, /* 0x3FC06EBA, 0x8214DB69 */ efx8= 1.02703333676410069053e+00, /* 0x3FF06EBA, 0x8214DB69 */ +/* + * Coefficients for approximation to erf on [0,0.84375] + */ pp0 = 1.28379167095512558561e-01, /* 0x3FC06EBA, 0x8214DB68 */ pp1 = -3.25042107247001499370e-01, /* 0xBFD4CD7D, 0x691CB913 */ pp2 = -2.84817495755985104766e-02, /* 0xBF9D2A51, 0xDBD7194F */ @@ -134,7 +141,7 @@ qq3 = 5.08130628187576562776e-03, /* 0x3F74D022, 0xC4D36B0F */ qq4 = 1.32494738004321644526e-04, /* 0x3F215DC9, 0x221C1A10 */ qq5 = -3.96022827877536812320e-06, /* 0xBED09C43, 0x42A26120 */ /* - * Coefficients for approximation to erf in [0.84375,1.25] + * Coefficients for approximation to erf in [0.84375,1.25] */ pa0 = -2.36211856075265944077e-03, /* 0xBF6359B8, 0xBEF77538 */ pa1 = 4.14856118683748331666e-01, /* 0x3FDA8D00, 0xAD92B34D */ @@ -150,7 +157,7 @@ qa4 = 1.26171219808761642112e-01, /* 0x3FC02660, 0xE763351F */ qa5 = 1.36370839120290507362e-02, /* 0x3F8BEDC2, 0x6B51DD1C */ qa6 = 1.19844998467991074170e-02, /* 0x3F888B54, 0x5735151D */ /* - * Coefficients for approximation to erfc in [1.25,1/0.35] + * Coefficients for approximation to erfc in [1.25,1/0.35] */ ra0 = -9.86494403484714822705e-03, /* 0xBF843412, 0x600D6435 */ ra1 = -6.93858572707181764372e-01, /* 0xBFE63416, 0xE4BA7360 */ @@ -169,7 +176,7 @@ sa6 = 1.08635005541779435134e+02, /* 0x405B28A3, 0xEE48AE2C */ sa7 = 6.57024977031928170135e+00, /* 0x401A47EF, 0x8E484A93 */ sa8 = -6.04244152148580987438e-02, /* 0xBFAEEFF2, 0xEE749A62 */ /* - * Coefficients for approximation to erfc in [1/.35,28] + * Coefficients for approximation to erfc in [1/.35,28] */ rb0 = -9.86494292470009928597e-03, /* 0xBF843412, 0x39E86F4A */ rb1 = -7.99283237680523006574e-01, /* 0xBFE993BA, 0x70C285DE */ @@ -222,15 +229,12 @@ erf(double x) x = fabs(x); s = one/(x*x); if(ix< 0x4006DB6E) { /* |x| < 1/0.35 */ - R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*( - ra5+s*(ra6+s*ra7)))))); - S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*( - sa5+s*(sa6+s*(sa7+s*sa8))))))); + R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*(ra5+s*(ra6+s*ra7)))))); + S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*(sa5+s*(sa6+s*(sa7+ + s*sa8))))))); } else { /* |x| >= 1/0.35 */ - R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*( - rb5+s*rb6))))); - S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*( - sb5+s*(sb6+s*sb7)))))); + R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*(rb5+s*rb6))))); + S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(sb5+s*(sb6+s*sb7)))))); } z = x; SET_LOW_WORD(z,0); @@ -238,6 +242,10 @@ erf(double x) if(hx>=0) return one-r/x; else return r/x-one; } +#if (LDBL_MANT_DIG == 53) +__weak_reference(erf, erfl); +#endif + double erfc(double x) { @@ -279,23 +287,23 @@ erfc(double x) x = fabs(x); s = one/(x*x); if(ix< 0x4006DB6D) { /* |x| < 1/.35 ~ 2.857143*/ - R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*( - ra5+s*(ra6+s*ra7)))))); - S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*( - sa5+s*(sa6+s*(sa7+s*sa8))))))); + R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*(ra5+s*(ra6+s*ra7)))))); + S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*(sa5+s*(sa6+s*(sa7+ + s*sa8))))))); } else { /* |x| >= 1/.35 ~ 2.857143 */ if(hx<0&&ix>=0x40180000) return two-tiny;/* x < -6 */ - R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*( - rb5+s*rb6))))); - S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*( - sb5+s*(sb6+s*sb7)))))); + R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*(rb5+s*rb6))))); + S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(sb5+s*(sb6+s*sb7)))))); } z = x; SET_LOW_WORD(z,0); - r = __ieee754_exp(-z*z-0.5625)* - __ieee754_exp((z-x)*(z+x)+R/S); + r = __ieee754_exp(-z*z-0.5625)*__ieee754_exp((z-x)*(z+x)+R/S); if(hx>0) return r/x; else return two-r/x; } else { if(hx>0) return tiny*tiny; else return two-tiny; } } + +#if (LDBL_MANT_DIG == 53) +__weak_reference(erfc, erfcl); +#endif |