What is 'esp'? a function? What it is meaning?

I downloaded a function imnoise2.m from http://www.mathworks.com/matlabcentral/fileexchange/28986-adding-noise-and-image-restoration/content/imnoise2.m

This file contains a function(?) 'esp' for generating lognormal random number. I surfed the internet but cannot find any answer for this. Who can tell me about this?

Answer 1

[Stephen23]

I suspect that it is a spelling mistake: exp.

[Xiaohua]

Thank you very much. I regreted that I should test it on Matlab before asking this stupid question.

[Stephen23]

"There is no such thing as stupid Questions, only stupid Answers"