Besides the suggestion to make sure the fortran code actually takes
REAL*8 instead of just REAL, I think your declaration and calling is
wrong. Fortran ``passes by reference'' but this really means ``passes
by pointer''. (At least this has always been the case when I mix C
and Fortran). So, I think your declaration should be:
extern "C" void herfasy_(double*,double*, double*,double*);
And you should call it like:
herfasy_(&Enbeam,&thetas,&omega,&asytt);
Luck,
-Brett.
Wang Xu writes:
> Dear Rooters,
> I try to link a fortran code(herasy.f) to the c++ code. The
> fortran code by itself works fine but if it link to this c++ code, one of
> subroutine of the fortran code dosen't give a right answer. Have you ever
> met same problem? If you did, please give me some suggestion as soon as
> possible.
> (I suspicious that I didn't put correct flag when I complie these two
> code. what I did is following:
> f77 -c herfasy.f *.f
> g++ -c acceptance.cxx
> g++ herfasy.o *.o acceptance.o -L/lib -l* -lg2c)
> Thanks,
> wang
> Here is the acceptance.cxx
> #include <stdio.h>
> #include <iostream.h>
>
> // ROOT include
> #include "TROOT.h"
> #include "TFile.h"
> #include "TNtuple.h"
> #include "TMath.h"
>
> extern "C" void herfasy_(double &,double &, double &,double &);
>
> int main()
> {
> TROOT accept("accept","accept");
> TFile *f = new
> TFile("/work/halla/e95001-2/wangxu/hbook/eq05/gmn_1pass_21067.root");
> TNtuple *h1 = (TNtuple*) f->Get("h1");
> Float_t asyt,thetat, yt, phit, deltat;
> double Enbeam,omega,thetas,asytt;
> Int_t nbytes;
> Enbeam=1.727;
> Float_t Eset=1.453;
> Float_t thed = 25.80;
> // Set branch addresses
> h1->SetBranchAddress("Ethetat", &thetat); // in mr
> h1->SetBranchAddress("Ephit", &phit); // in mr
> h1->SetBranchAddress("Eyt", &yt); // in mm
> h1->SetBranchAddress("Edelta", &deltat); // in %
> TFile *acceptance = new TFile("acceptance.root", "RECREATE");
> TNtuple *ntuple = new TNtuple("ntuple", "Asymetry Study",
> "Ethetat:Ephit:Eyt:Edelta:asyt");
> // Total event number
> //Int_t nentries = (Int_t) h1->GetEntries();
> Int_t nentries=1;
> for(Int_t i=0; i<nentries; i++) {
> nbytes += h1->GetEvent(i);
> thetas=acos(cos(thed*3.1415926/180+phit/1000)*cos(thetat/1000));
> thetas= thetas*180/3.1415926;
> omega=Enbeam-Eset*(1+deltat/100);
> herfasy_(Enbeam,thetas,omega,asytt);
> asyt=asytt;
> printf("%f\n",asyt);
> ntuple->Fill(thetat,phit,deltat,asyt);
> }
> ntuple->Write();
> f->Close();
> acceptance->Close();
> return(0);
> }
>
>
>
>
>
>
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