Hi,
I have been racking my brain over this segmentation fault for a few
days now and tracked it down to gsl_integration_qag. The strange thing
is that the segmentation fault only happens after n and m = 37. I did
try increasing the size of my work space but that didn't seem to do
much of anything at all. Any suggestions? I'm sure the error is
something thats obvious to someone more experienced with the gsl.
I have included the code below:
int N = 50; //Starting size
double sum = 0.0;
int j = 0;
int sizeN = 2*N+1; //Size
mat HN(sizeN,sizeN); //Defines the hamiltonian matrix
gsl_integration_workspace * w = gsl_integration_workspace_alloc
(100000);
double result1,result2, error;
gsl_function F1;
struct my_f_params alpha = {2,2};
F1.function = &f1;
F1.params = α
for(int n = 0; n <= sizeN; n++)
for(int m = 0; m <= sizeN; m++)
{
alpha.a = n;
alpha.b = m;
gsl_integration_qag (&F1, 0, 6, 0, 1e-4, 1000, GSL_INTEG_GAUSS61,w,
&result1, &error);
gsl_integration_qag (&F1, -6, 0, 0, 1e-4, 1000,
GSL_INTEG_GAUSS61,w, &result2, &error);
cout << m << " " << n << endl;
HN(n,m) = result1 + result2;
}
with f1 being
double f1 (double x, void * p) { //Deriviative part of the integral
struct my_f_params * params = (struct my_f_params *)p;
int n = (params->a);
int m = (params->b);
double f = exp(-(x*x))*hermitecalculate(m,x)*( (-1.0)*((4*n*n -
4*n)*hermitecalculate(n-2,x) - 4*n*hermitecalculate(n-1,x)*x -
hermitecalculate(n,x) + hermitecalculate(n,x)*x*x));
f += exp(-x*x)*hermitecalculate(n,x)*hermitecalculate(m,x)*(pow(x,
6.0) + 4*pow(x,4) + x*x - 2);
return f/
(sqrt
(gsl_sf_fact
(n)*sqrt(pi)*pow(2.0,n))*sqrt(gsl_sf_fact(m)*sqrt(pi)*pow(2.0,m)));
}
and my_f_params defined as
struct my_f_params {int a; int b;};
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