#include <origin.h>
// Add your special include files here.
// For example, if you want to fit with functions from the NAG library, 
// add the header file for the NAG functions here.
#include <oc_nag8.h>
 
 
// Add code here for other Origin C functions that you want to define in this file,
// and access in your fitting function.
struct user
{
	double a, b, fitX;  // fitX the independent variable of fitting function
 
};
static double NAG_CALL f_callback(double x, Nag_User *comm)  // x is the independent variable of the integrand
{
 
	struct user *sp = (struct user *)(comm->p);
 
        double aa, bb, fitX, Gas, beta, tau; // temp variable to accept the parameters in the Nag_User communication struct
        aa = sp->a; // a = Frequency Factor, b = Energy in J/mol, fitX = Temperature T inside integral, 
        bb = sp->b; // Gas = Gas constant in J/K mol, beta = Heating Rate, tau = V/S Vacuum constant;
        fitX = sp->fitX;
        Gas = 8.314;
        beta = 19;
        tau = 0.65;
 
        return exp(fitX/(beta*tau))*exp(-bb/(Gas*fitX))*exp((-aa*Gas*fitX*fitX*exp(-bb/(Gas*fitX)))/(beta*bb));
}
 
// You can access C functions defined in other files, if those files are loaded and compiled 
// in your workspace, and the functions have been prototyped in a header file that you have
// included above. 
 
// You can access NLSF object methods and properties directly in your function code.
 
// You should follow C-language syntax in defining your function. 
// For instance, if your parameter name is P1, you cannot use p1 in your function code. 
// When using fractions, remember that integer division such as 1/2 is equal to 0, and not 0.5
// Use 0.5 or 1/2.0 to get the correct value.
 
// For more information and examples, please refer to the "User-Defined Fitting Function" 
// section of the Origin Help file.

// 
// 

//----------------------------------------------------------
// 
void _nlsfPWwithparametric(
// Fit Parameter(s):
double a, double b, double c, double d, double y0,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
	// Beginning of editable part
	// Beginning of editable part
	double epsabs = 0.00001, epsrel = 0.0000001, result, abserr;
	double beta, tau;
	beta = 19;
	tau = 0.65;
	Integer max_num_subint = 5000;  
	        // you may use epsabs and epsrel and this quantity to enhance your desired precision 
	        // when not enough precision encountered
	 
	Nag_QuadProgress qp;
	static NagError fail;
	 
	// the parameters parameterize the integrand can be input to the call_back function
	        // through the Nag_User communication struct 
	        Nag_User comm;	
	struct user s;
	s.a = a;
	s.b = b;
	s.fitX = x;
	        comm.p = (Pointer)&s;
	 
	d01sjc(f_callback, c, s.fitX, epsabs, epsrel, max_num_subint, &result, &abserr, &qp, &comm, &fail);
	 
	 
	        // you may want to exam the error by printing out error message, just uncomment the following lines
	// if (fail.code != NE_NOERROR)
	        // printf("%s\n", fail.message);
	 
	 
	// 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);
	}
	 
	 
	y = y0+d*(a/beta)*(exp(-x/(beta*tau)))*result; 
	// End of editable part
}