Using the igesout and stlwrite functions in MATLAB

I wanted to export a MATLAB representation of a gyroid surface as an STL or IGES file format, and I was suggested to use the 'igesout' and 'stlwrite' functions for that. But i still couldn't figure out how to use these functions. Can anyone help me on this or maybe try the function. I have attached the MATLAB file I used to generate the surface and the functions. Thank you