The following Matlab project contains the source code and Matlab examples used for log factorial of large positive numbers. Matlab doesn't provide the values of n! when n>170, but this code can evaluate the logarithm of of n! with absolute accuracy of 1e-12 or better, and relative accuracy of 1e-15 or better.
The source code and files included in this project are listed in the project files section, please make sure whether the listed source code meet your needs there.