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Tested under MSVC by nkshigeru. Minor code formatting

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This commit is contained in:
Paolo Bosetti
2012-05-15 23:55:44 -07:00
parent 4bc4807297
commit b9b20c8be8
1 changed files with 25 additions and 19 deletions
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src/math.c
+25 -19
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@@ -11,6 +11,7 @@
mrb_raise(mrb, E_RANGE_ERROR, "Numerical argument is out of domain - " #msg);
/* math functions not provided under Microsoft Visual C++ */
#define _MSC_VER
#ifdef _MSC_VER
#define asinh(x) log(x + sqrt(pow(x,2.0) + 1))
#define acosh(x) log(x + sqrt(pow(x,2.0) - 1))
@@ -30,18 +31,20 @@ erfc(double x);
double
erf(double x)
{
static const double two_sqrtpi= 1.128379167095512574;
double sum= x, term= x, xsqr= x*x;
static const double two_sqrtpi = 1.128379167095512574;
double sum = x;
double term = x;
double xsqr = x*x;
int j= 1;
if (fabs(x) > 2.2) {
return 1.0 - erfc(x);
}
do {
term*= xsqr/j;
sum-= term/(2*j+1);
term *= xsqr/j;
sum -= term/(2*j+1);
++j;
term*= xsqr/j;
sum+= term/(2*j+1);
term *= xsqr/j;
sum += term/(2*j+1);
++j;
} while (fabs(term)/sum > REL_ERROR);
return two_sqrtpi*sum;
@@ -52,10 +55,13 @@ double
erfc(double x)
{
static const double one_sqrtpi= 0.564189583547756287;
double a=1, b=x;
double c=x, d=x*x+0.5;
double q1,q2;
double n= 1.0, t;
double a = 1;
double b = x;
double c = x;
double d = x*x+0.5;
double q1, q2;
double n = 1.0;
double t;
if (fabs(x) < 2.2) {
return 1.0 - erf(x);
}
@@ -63,15 +69,15 @@ erfc(double x)
return 2.0 - erfc(-x);
}
do {
t= a*n+b*x;
a= b;
b= t;
t= c*n+d*x;
c= d;
d= t;
n+= 0.5;
q1= q2;
q2= b/d;
t = a*n+b*x;
a = b;
b = t;
t = c*n+d*x;
c = d;
d = t;
n += 0.5;
q1 = q2;
q2 = b/d;
} while (fabs(q1-q2)/q2 > REL_ERROR);
return one_sqrtpi*exp(-x*x)*q2;
}