Example macro describing how to use the special mathematical functions taking full advantage of the precision and speed of the C99 compliant environments.
To execute the macro type in:
root[0] .x mathcoreSpecFunc.C
It will create two canvases:
- one with the representation of the tgamma, lgamma, erf and erfc functions
- one with the relative difference between the old ROOT versions and the C99 implementation (on obsolete platform+compiler combinations which are not C99 compliant it will call the original ROOT implementations, hence the difference will be 0)
The naming and numbering of the functions is taken from [Matt Austern, (Draft) Technical Report on Standard Library Extensions, N1687=04-0127, September 10, 2004](A HREF="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1687.pdf")
void mathcoreSpecFunc() {
TF1 *f1a =
new TF1(
"f1a",
"ROOT::Math::tgamma(x)",0,20);
TF1 *f1b =
new TF1(
"f1b",
"abs((ROOT::Math::tgamma(x)-TMath::Gamma(x))/ROOT::Math::tgamma(x))",0,20);
TF1 *f2a =
new TF1(
"f2a",
"ROOT::Math::lgamma(x)",0,100);
TF1 *f2b =
new TF1(
"f2b",
"abs((ROOT::Math::lgamma(x)-TMath::LnGamma(x))/ROOT::Math::lgamma(x))",0,100);
TF1 *f3a =
new TF1(
"f3a",
"ROOT::Math::erf(x)",0,5);
TF1 *f3b =
new TF1(
"f3b",
"abs((ROOT::Math::erf(x)-TMath::Erf(x))/ROOT::Math::erf(x))",0,5);
TF1 *f4a =
new TF1(
"f4a",
"ROOT::Math::erfc(x)",0,5);
TF1 *f4b =
new TF1(
"f4b",
"abs((ROOT::Math::erfc(x)-TMath::Erfc(x))/ROOT::Math::erfc(x))",0,5);
}
virtual void SetLineColor(Color_t lcolor)
Set the line color.
virtual void Draw(Option_t *option="")
Draw this function with its current attributes.
- Author
- Andras Zsenei
Definition in file mathcoreSpecFunc.C.