Origin has included all functions from NAG MARK C LIBRARY since Origin 8 released. These functions can be easily accessed from your Origin C function. In Origin 2017, the NAG library has been updated to the latest version Mark 25.

Linked Jira:  

SummaryDetails
The header file <oc_nag8.h> is replaced by <OC_nag.h>, and the header file <oc_nag_ex.h> is withdrawn.

For example:

#include <OC_nag8.h>
#include <nag\OC_nag_ex.h>

need to be changed into:

#include <OC_nag.h>
//#include <nag\OC_nag_ex.h>//not need, only oc_nag.h required.