diff options
Diffstat (limited to 'src/math/erf.c')
| -rw-r--r-- | src/math/erf.c | 57 |
1 files changed, 27 insertions, 30 deletions
diff --git a/src/math/erf.c b/src/math/erf.c index 18ee01cf..dd8c3a77 100644 --- a/src/math/erf.c +++ b/src/math/erf.c @@ -107,9 +107,6 @@ 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 */ erx = 8.45062911510467529297e-01, /* 0x3FEB0AC1, 0x60000000 */ /* @@ -190,7 +187,7 @@ double erf(double x) if (ix >= 0x7ff00000) { /* erf(nan)=nan, erf(+-inf)=+-1 */ i = ((uint32_t)hx>>31)<<1; - return (double)(1-i) + one/x; + return (double)(1-i) + 1.0/x; } if (ix < 0x3feb0000) { /* |x|<0.84375 */ if (ix < 0x3e300000) { /* |x|<2**-28 */ @@ -201,42 +198,42 @@ double erf(double x) } z = x*x; r = pp0+z*(pp1+z*(pp2+z*(pp3+z*pp4))); - s = one+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5)))); + s = 1.0+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5)))); y = r/s; return x + x*y; } if (ix < 0x3ff40000) { /* 0.84375 <= |x| < 1.25 */ - s = fabs(x)-one; + s = fabs(x)-1.0; P = pa0+s*(pa1+s*(pa2+s*(pa3+s*(pa4+s*(pa5+s*pa6))))); - Q = one+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6))))); + Q = 1.0+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6))))); if (hx >= 0) return erx + P/Q; return -erx - P/Q; } if (ix >= 0x40180000) { /* inf > |x| >= 6 */ if (hx >= 0) - return one-tiny; - return tiny-one; + return 1.0 - tiny; + return tiny - 1.0; } x = fabs(x); - s = one/(x*x); + s = 1.0/(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*( + S = 1.0+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*( + S = 1.0+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*( sb5+s*(sb6+s*sb7)))))); } z = x; SET_LOW_WORD(z,0); r = exp(-z*z-0.5625)*exp((z-x)*(z+x)+R/S); if (hx >= 0) - return one-r/x; - return r/x-one; + return 1.0 - r/x; + return r/x - 1.0; } double erfc(double x) @@ -248,49 +245,49 @@ double erfc(double x) ix = hx & 0x7fffffff; if (ix >= 0x7ff00000) { /* erfc(nan)=nan, erfc(+-inf)=0,2 */ - return (double)(((uint32_t)hx>>31)<<1) + one/x; + return (double)(((uint32_t)hx>>31)<<1) + 1.0/x; } if (ix < 0x3feb0000) { /* |x| < 0.84375 */ if (ix < 0x3c700000) /* |x| < 2**-56 */ - return one - x; + return 1.0 - x; z = x*x; r = pp0+z*(pp1+z*(pp2+z*(pp3+z*pp4))); - s = one+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5)))); + s = 1.0+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5)))); y = r/s; if (hx < 0x3fd00000) { /* x < 1/4 */ - return one - (x+x*y); + return 1.0 - (x+x*y); } else { r = x*y; - r += x-half; - return half - r ; + r += x - 0.5; + return 0.5 - r ; } } if (ix < 0x3ff40000) { /* 0.84375 <= |x| < 1.25 */ - s = fabs(x)-one; + s = fabs(x)-1.0; P = pa0+s*(pa1+s*(pa2+s*(pa3+s*(pa4+s*(pa5+s*pa6))))); - Q = one+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6))))); + Q = 1.0+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6))))); if (hx >= 0) { - z = one-erx; + z = 1.0-erx; return z - P/Q; } else { z = erx+P/Q; - return one+z; + return 1.0 + z; } } if (ix < 0x403c0000) { /* |x| < 28 */ x = fabs(x); - s = one/(x*x); + s = 1.0/(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*( + S = 1.0+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) /* x < -6 */ - return two-tiny; + return 2.0 - tiny; 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*( + S = 1.0+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*( sb5+s*(sb6+s*sb7)))))); } z = x; @@ -298,9 +295,9 @@ double erfc(double x) r = exp(-z*z-0.5625)*exp((z-x)*(z+x)+R/S); if (hx > 0) return r/x; - return two-r/x; + return 2.0 - r/x; } if (hx > 0) return tiny*tiny; - return two-tiny; + return 2.0 - tiny; } |