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annalisabranca
Netherlands
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 Posted - 10/14/2008 : 11:54:44 AM
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Hi!
I'm using Origin 8 SR0.
I read the other questions on the same topic, but I'm still lost, since I'm new to programming  .
Expression:
y=Intagrate{(exp[(-x^2*L^2)/(16*Pi^2)]*(4*Pi*x^2))/(((w-(w0-120*(x/(2*Pi/a0))^2))^2)+(G/2)^2}; dx
integration boundaries : 2*Pi/a0 (upper), 0 (lower)
y is the dependent variable, x the indipendent variable and all the others are parameters.
The data of the spectra that I need to fit are on 2 columns: column A wavelength (x axis), column B intensity (y axis)
Some help for the code?
Thank you in advance!
LisaB |
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Hideo Fujii
USA
1582 Posts |
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annalisabranca
Netherlands
Posts |
Posted - 10/21/2008 : 12:12:37 PM
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Hi Hideo Fujii
Thanks for your help. I updated my Origin8 to SR4 version.
I also tried to use the tutorials you linked, but I still have a problem. I am able to compile it, but when I simulate it, nothing changes (whatever parameters I put in), it just stays a straight line at 0. I am sure that the function is correct cause it is reported in many scientific articles, so it might be a matter of code. Could you have a look on the code I wrote? I am not able to find what is wrong.
This is what Ifve done:
Thanks again!
Lisa
I need to program this fitting function
Where:
q0=2/5.483
L (size),w0,C(width) are parameters
w(centre) is the independent variable of the fitting function
x is the independent variable of the integrand
#pragma warning(error : 15618)
#include <origin.h>
#include <oc_nag8.h>
#define NAG_FREE(X) x04bdc((Pointer *)&(X))
// Add code here for other Origin C functions that you want to define in this file,
// and access in your fitting function.
struct user // parameters in the integrand
{
double size, center, width,w0;
};
// Function supplied by user, return the value of the integrand at a given x.
static double NAG_CALL f_callback(double x, Nag_User *comm)
{
struct user *sp = (struct user *)(comm->p);
double size, center, width,w0; // temp variable to accept the parameters in the Nag_User communication struct
size = sp->size;
center = sp->center;
width = sp->width;
w0 = sp->w0;
return (exp((-x*x*size*size)/(16*PI*PI))*4*PI*x*x)/((((center-(w0-120*(x/(2*PI/5.483))*(x/(2*PI/5.483)))))*((center-(w0-120*(x/(2*PI/5.483))*(x/(2*PI/5.483))))))+(width/2)*(width/2));
}
//----------------------------------------------------------
void _nlsfnag_integration_fitting(
// Fit Parameter(s):
double L, double g, double w0,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
// Beginning of editable part
double epsabs = 0.0, epsrel = 0.0001;
double a=0;
double b=2*PI/5.483;
Integer max_num_subint = 500;
// Result keeps the approximate integral value returned by the algorithm
double result, abserr;
// The structure of type Nag_QuadProgress,
// it contains pointers allocated memory internally with max_num_subint elements
Nag_QuadProgress qp;
// The NAG error parameter (structure)
static NagError fail;
// Parameters passed to integrand by Nag_User communication struct
Nag_User comm;
struct user s;
s.size = L;
s.center = x;
s.width = g;
s.w0 = w0;
comm.p = (Pointer)&s;
// Perform integration
d01smc(f_callback,a,b, epsabs, epsrel, max_num_subint, &result, &abserr, &qp, &comm, &fail);
// For the error other than the following three errors which are due to bad input parameters
// or allocation failure NE_INT_ARG_LT NE_BAD_PARAM NE_ALLOC_FAIL
// You will need to free the memory allocation before calling the integration routine again to avoid memory leakage
if (fail.code != NE_INT_ARG_LT && fail.code != NE_BAD_PARAM && fail.code != NE_ALLOC_FAIL)
{
NAG_FREE(qp.sub_int_beg_pts);
NAG_FREE(qp.sub_int_end_pts);
NAG_FREE(qp.sub_int_result);
NAG_FREE(qp.sub_int_error);
}
// Calculate the fitted value
y = result;
// End of editable part
}
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annalisabranca
Netherlands
Posts |
Posted - 10/22/2008 : 05:28:34 AM
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Hi!
I found the mistake!
Still thanks a lot! |
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Topic |
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Fitting function with integral