Problem with IsNan

Hi,
I tried to use the function IsNan() in an interactive section of Root like this:

int out = TMath::IsNan((double)pol_y_fit_pt_1);

and I get the following error message:

Error: class,struct,union or type $TMath not defined FILE:root_scripts/draw_pt_polarization.C LINE:50
Error: class,struct,union or type $TMath not defined FILE:root_scripts/draw_pt_polarization.C LINE:50
Error: Function IsNan((double)pol_y_fit_pt_1) is not defined in current scope FILE:root_scripts/draw_pt_polarization.C LINE:50

I tried to include ctype.h in the macro but no action was taken by the macro.
Could you say anything to solve this problem, please?
Thanks
[-o<

You have a typo.
It must be IsNaN and not IsNan

Rene