double norm_cdf(double x, double mu = 0, double sigma = 1)
{
	if( sigma > 0 )
		return nag_cumul_normal( ( x - mu ) / sigma );
	else
		return NANUM;
}

quote:

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Hi,

The cumulative normal distribution function is available in the NAG library under the function named nag_cumul_normal(x). You can call this function from your custom fitting function in NLSF. Note that to call the NAG function in your NLSF fitting function, you should first edit your fitting function in code builder (click the Edit in Code Builder button in the NLSF tool), and then replace all the #include statements at the top of the function with just one statement:
#include <origin.h>

Now, the nag_cumul_normal() function assumes a mu (centroid) of zero and sigma (std dev) of 1. So if you want something more general, I suggest that you define a new Origin C function as follows:

1> Go to code builder and start a new C file - give it a name say for example MyFunctions.c
2> Add the following function to that file and compile

double norm_cdf(double x, double mu = 0, double sigma = 1)
{
	if( sigma > 0 )
		return nag_cumul_normal( ( x - mu ) / sigma );
	else
		return NANUM;
}

3> Now your new function norm_cdf() will allow computing the cumulative distribution for a specified mu and sigma
4> In Code Builder, drag-and-drop the file from the User folder to the System folder. Then this function will be available any time you launch Origin
5> Then, in NLSF, you can refer to this function in your custom fitting function code using the syntax
norm_cdf(x, mu, sigma). Note that mu and sigma default to 0 and 1 respectively if not specified.

Easwar
OriginLab

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