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ttanhfr
3 Posts |
 Posted - 01/28/2013 : 03:23:57 AM
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Origin Ver. and Service Release (Select Help-->About Origin): OriginPro 8.5.1
Operating System:Windows XP
I have a data as follows:
x y
695 5306
696 5278
697 5292
698 5476
699 5611
700 5799
701 6557
702 7908
703 10849
704 14896
705 19283
706 22559
707 25163
708 26579
709 27061
710 27802
711 27817
712 27923
713 27809
714 27792
715 27664
716 27817
717 27257
718 27481
719 26872
720 26725
721 25463
722 23203
723 20041
724 16121
725 11754
726 8198
727 6396
728 5420
729 5379
730 5564
731 5403
732 5167
I want to fit data with a function:
F2(E)=N2*integral(0,PI){exp(-(x-xc+k*cos(t))^2/2/w^2)*sin(t)dt}
where k=11.424
A:peak amplitute
xc=E0: centroid peak
w: peak width
t=theta: recoil angle
Could you show me how to create this function in OriginLab.
Thank you.
http://www.originlab.com/ftp/forum_and_kbase/Images/B.pdf |
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Penn
China
644 Posts |
Posted - 01/28/2013 : 8:45:27 PM
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Hi,
You can refer to this tutorial.
Penn |
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ttanhfr
3 Posts |
Posted - 01/31/2013 : 02:06:44 AM
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Hi,
Thank you Penn.
Following the tutorial, I create a new function as follows:
#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 amp, center, width, angle, v0, c;
};
// 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 amp, center, width, angle, v0, c; // , angle, v0, c temp variable to accept the parameters in the Nag_User communication struct
amp = sp->amp;
center = sp->center;
width = sp->width;
angle = sp->angle;
v0=4.8E+6;
c=3.0E+8;
return amp * exp( -0.5*(x - center + (center * v0/c) * cos(angle))*(x - center + (center * v0/c) * cos(angle))/width/width )*sin(angle);
}
// 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 _nlsfBoronPeakFitting(
// Fit Parameter(s):
double y0, double A, double xc, double w, double theta,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y,
// Partial Derivative(s):
double& dy_y0, double& dy_A, double& dy_xc, double& dy_w, double& dy_theta)
{
// 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.amp = A;
s.center = xc;
s.width = w;
s.angle = theta;
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
d01smc(f_callback, Nag_LowerSemiInfinite, 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 value
y = y0 + result;
// End of editable part
}
The result could not be obtained. Something wrong?
Anyone can check it for me.
Thank you. |
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How to create a new function