float gammp(float a, float x)
{
if(x < 0.0 || a <= 0.0)
printf("bad args in gammp\n");
if(x == 0.0)
return 0.0;
else if((int) a >= ASWITCH)
return gammpapprox(a, x, 1);
else if(x < a + 1.0)
return gser(a, x);
else
return 1.0 - gcf(a, x);
}
double gammq(double a, double x)
{
if(x < 0.0 || a <= 0.0)
printf("bad args in gammq\n");
if(x == 0.0)
return 1.0;
else if((int) a >= ASWITCH)
return gammpapprox(a, x, 0);
else if(x < a + 1.0)
return 1.0 - gser(a, x);
else
return gcf(a, x);
}
double gammp(const double a, double x) {
static const int ASWITCH = 100;
if(x < 0.0 || a <= 0.0) {
std::cout << "Bad value in Fgamma!";
return 0.0;
}
if(x == 0.0) {
return 0.0;
} else if(a >= ASWITCH) {
return gammpapprox(a,x,1); /* use quadrature */
} else if(x < a + 1.0) {
return gser(a,x); /* use the series expansion */
} else {
return 1.0 - gcf(a,x); /* use the continued fraction expansion */
}
}