Re: bug in root/cint with TF2::GetRandom2 and user defined function

Rene Brun (Rene.Brun@cern.ch)
Mon, 18 Jan 1999 08:08:35 +0100

stefan kluth wrote:
>
> Hi,
>
> I have found a problem when using TF2::GetRandom2 with a user defined
> function. I use root 2.20/06. I get a " *** Break *** segmentation
> violation " in root, when I try to call TF2::GetRandom2 from a TF2 object
> constructed with a pointer to a user defined function. Other member
> functions like TF2::Draw work fine. The following macro demonstrates the
> problem:
>
> double gausxy( double* x, double* par ) {
>
> double dxds= (x[0]-par[0])/par[2];
> double dyds= (x[1]-par[1])/par[3];
> double rho= par[4];
> return exp( -0.5*( dxds*dxds + dyds*dyds
> - 2.0*dxds*dyds*rho )/( 1.0-rho*rho) );
>
> }
> void myfunc2() {
>
> TF2* f2= new TF2( "myfunc2", gausxy, -10, 10, -10, 10, 5 );
> f2->SetParameter( 0, 0.0 );
> f2->SetParameter( 1, 0.0 );
> f2->SetParameter( 2, 2.0 );
> f2->SetParameter( 3, 2.0 );
> f2->SetParameter( 4, 0.1 );
> f2->Draw();
> Float_t xmf, ymf;
> printf( "Now calling GetRandom2\n" );
> f2->GetRandom2( xmf, ymf );
>
> }
>
> The same call to TF2::GetRandom2 works fine when the function is given
> at the costruction of the TF2 object by a formula string.
>
> cheers, Stefan

Hi Stefan,
Thanks for reporting this problem with TF2::GetRandom2 when using
an interpreted function.
I have fixed this problem in 2.21/02

Rene Brun