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 Topic  |
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Estitxu
13 Posts |
 Posted - 08/06/2013 : 05:26:49 AM
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Hi,
I'm using Origin 8.5 and I need to fit an integral function, which inside the integrand has a Heaviside function. I don't find the Heaviside function in this version of Origin, so I'm trying to define it myself... The function I need to fit is the following:
I tried defining the step function in two ways, but I have some compilation errors which I don't know where they come from! I used the following two codes:
CODE 1:
#pragma warning(error : 15618)
#include <origin.h>
#include <oc_nag8.h>
#define NAG_FREE(X) x04bdc((Pointer *)&(X))
// 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.
// 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 e, EF, KT, Vb, fitX; // fitX the independent variable of fitting function
double x0=EF-e*x+e*Vb;
double step(double FitX, double x0) {
return (fitX<x0?0:(fitX==x0?1:1));
}
};
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 ee, EE, KK, VV, fitX; // temp variable to accept the parameters in the Nag_User communication struct
e= sp->e;
EF = sp->EF;
KT = sp->KT;
Vb = sp->Vb;
x0 = sp->x0;
fitX = sp->fitX;
return (1/(1+exp(fitX/KT))-1/(1+exp((fitX-e*x)/KT)))*step(fitX,x0);
}
// 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 _nlsfnag_integration_marco(
// Fit Parameter(s):
double e, double EF, double KT, double R, double Vb,
// Independent Variable(s):
double x, double It,
// Dependent Variable(s):
double& y)
{
// Beginning of editable part
double epsabs = 0.00001, epsrel = 0.0000001, result, abserr;
Integer max_num_subint = 500;
// 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.e = e;
s.EF = EF;
s.KT = KT;
s.Vb = Vb;
s.fitX = x;
comm.p = (Pointer)&s;
d01sjc(f_callback, Nag_LowerSemiInfinite, Nag_UpperSemiInfinite, 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 = R*It*result;
// note use log of the integral result as return as the integral result is large,
// you are not necessary to do so
// End of editable part
}
CODE 2:
#pragma warning(error : 15618)
#include <origin.h>
#include <oc_nag8.h>
#define NAG_FREE(X) x04bdc((Pointer *)&(X))
// 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.
// 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 e, EF, KT, Vb, 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 ee, EE, KK, VV, fitX; // temp variable to accept the parameters in the Nag_User communication struct
ee = sp->e;
EE = sp->EF;
KK = sp->KT;
VV = sp->Vb;
fitX = sp->fitX;
return
{ if(fitX<EE-ee*x+ee*VV) {
return 0;
} else {
return (1/(1+exp(fitX/KK))-1/(1+exp((fitX-ee*x)/KK)));
}
}
}
// 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 _nlsfCopyOfnag_integration_marco(
// Fit Parameter(s):
double e, double EF, double KT, double R, double Vb,
// Independent Variable(s):
double x, double It,
// Dependent Variable(s):
double& y)
{
// Beginning of editable part
double epsabs = 0.00001, epsrel = 0.0000001, result, abserr;
Integer max_num_subint = 500;
// 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.e = e;
s.EF = EF;
s.KT = KT;
s.Vb = Vb;
s.fitX = x;
comm.p = (Pointer)&s;
d01sjc(f_callback, Nag_LowerSemiInfinite, Nag_UpperSemiInfinite, 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 = R*It*result;
// note use log of the integral result as return as the integral result is large,
// you are not necessary to do so
// End of editable part
}
Do you know what's wrong? Or do you know how I could improve them?? (of course it's enough with one of them as long as it works ;) )
Thanks a lot!! |
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Estitxu
13 Posts |
Posted - 08/06/2013 : 05:32:28 AM
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Sorry, I should have put x (indep. parameter) instead of V in the function!! so the function I wanna fit is the following:
The rest is on the previous post! thanks again!! |
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Sam Fang
291 Posts |
Posted - 08/07/2013 : 05:57:08 AM
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Function body for NAG_CALL f_callback in CODE 2 can be changed as:
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 ee, EE, KK, VV, fitX; // temp variable to accept the parameters in the Nag_User communication struct
ee = sp->e;
EE = sp->EF;
KK = sp->KT;
VV = sp->Vb;
fitX = sp->fitX;
/*return
{ if(fitX<EE-ee*x+ee*VV) {
return 0;
} else {
return (1/(1+exp(fitX/KK))-1/(1+exp((fitX-ee*x)/KK)));
}
}*/
if(fitX<EE-ee*x+ee*VV)
{
return 0;
}
else
{
return (1/(1+exp(fitX/KK))-1/(1+exp((fitX-ee*x)/KK)));
}
}
Sam
OriginLab Technical Services |
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Estitxu
13 Posts |
Posted - 08/07/2013 : 09:41:46 AM
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Hi Sam,
thanks for your help! Now I can compile the function, but I can not get to do the fitting. I want to fit R and Vb, the last one is inside the Heaviside function and it seems that the function is independent of its value!
What I mean is that when I do the fitting, the program only fits R's value and leaves the initial value of Vb unchanged. And regardless the initial value of Vb that I put (in a range between 0.1 and 100), the fitted value of R doesn't change!
Do you know where the problem can be??
Thanks again!!
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Sam Fang
291 Posts |
Posted - 08/09/2013 : 02:28:26 AM
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You can try to change Vb in a larger range. In fact as long as fitX>EE-ee*x+ee*VV, all VV can get the same result.
If it still fails, you can send your fitting data to us. To send a file to us, click Send File to Tech support on the top right of the forum.
Sam
OriginLab Technical Services |
Edited by - Sam Fang on 08/09/2013 02:29:11 AM |
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Integral fitting with heaviside function