Create your own fitting functions using Igor Pro's built-in programming language.
Igor Pro's New Fit Function dialog helps you create fitting functions. You just type arithmetic expressions.
User-defined fitting functions can be arbitrarily complex, involving conditionals, loops, convolution, solutions of ODE's, etc.
Time-consuming fit functions can be implemented in C or C++ using the XOP Toolkit.
Igor Pro 9
Igor XOP Toolkit
Igor NIDAQ Tools MX