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edwardclhuang
Taiwan
9 Posts |
 Posted - 11/24/2011 : 4:53:29 PM
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Origin Ver. and Service Release (Select Help-->About Origin): 8, SR4
Operating System:Win7 64 bit
Dear Sir
After reading the tutorials of NAG, I still have problems in the fitting with integration because I have a fitting parameter in the upper bound. Please see the attached function. I have tried to write the fitting function with NAG as following.
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#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 // parameters in the integrand
{
double thetaD;
};
// Function supplied by user, return the value of the integrand at a given x.
static double NAG_CALL f_callback(double thetaD/x, Nag_User *comm)
{
struct user *sp = (struct user *)(comm->p);
double thetaD; // temp variable to accept the parameters in the Nag_User communication struct
thetaD = sp->thetaD;
return (thetaD/x)^4*exp(thetaD/x)/((exp(thetaD/x)-1)^2);
}
// 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 _nlsfDebyeTermandlectronic(
// Fit Parameter(s):
double A0, double TD,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
// Beginning of editable part
// Through the absolute accuracy epsabs, relative accuracy epsrel and max_num_subint you can
// control the precision of the integration you need
// if epsrel is set negative, the absolute accuracy will be used.
// Similarly, you can control only relative accuracy by set the epsabs negative
double epsabs = 0.0, epsrel = 0.0001;
// The max number of sub-intervals needed to evaluate the function in the integral
// The more diffcult the integrand the larger max_num_subint should be
// For most problems 200 to 500 is adequate and recommmended
Integer max_num_subint = 200;
// Result keeps the approximate integral value returned by the algorithm
// abserr is an estimate of the error which should be an upper bound for the |I - result|
// where I is the integral value
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.thetaD = TD;
comm.p = (Pointer)&s;
// Perform integration
// There are 3 kinds of infinite boundary types you can use in Nag infinite integrator
// Nag_LowerSemiInfinite, Nag_UpperSemiInfinite, Nag_Infinite
d01sjc(f_callback, 0, TD/x, 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);
}
// Calculate the fitted valu
y=A0*x+9*3*8.3145*(x/TD)^3*result
// End of editable part
}
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Of course I can not compile this successfully. Because, as in the bold part, I use "double thetaD/x" which is definitely wrong. However in my integration, the formula continuously integrate until a converge value and with choosing a proper TD. One of your engineer taught me I may try to replace thetaD/x by x', but in this case I may not know A0, another fitting parameter, and that's not what I want.
Please help me solve the problem. Thanks so much for your help.
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integration fitting with parameter in bound
