Hi Hisham,
Let me take a simple example:
1. I will fit the following model as illustrated:
2. Press F9 to open the Fitting Function Organizer dialog and then create a new function as below:
3. Click the button beside the Function box to open the code builder
4. Add the header file for the NAG functions.
#include <OC_nag.h>
5.Define your fitting model.
static double NAG_CALL f(Integer n, double z[], Nag_User *comm)
{
double tmp_pwr;
tmp_pwr = z[0]+z[1];
return tmp_pwr;
}
6.Edit your fitting function.
void _nlsfnag_integration_fitting(
// Fit Parameter(s):
double amp,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
// Beginning of editable part
Integer ndim = 2; // the integral dimension
Integer maxpts = 1000*2; // maximum number of function evaluation
double a[4], b[4];
Integer k;
static NagError fail;
double finval;
Integer minpts;
double acc, eps;
Nag_User comm;
for (k=0; k < 2; ++k) // integration interval
{
a[k] = amp;
b[k] = x;
}
eps = 0.0001; // set the precision
minpts = 0;
d01wcc(ndim, f, a, b, &minpts, maxpts, eps, &finval, &acc, &comm, &fail);
y = finval;
// End of editable part
}
7. Click Compile button, and then Return to Dialog
8. Click Save button
9. Click Simulate button to check the fitting function
Hope it helps.
Regards,
Yuki
OriginLab
Double integral fit
Posted - 12/22/2016 : 2:16:45 PM
