If you use this code for a publication, please acknowledge the original paper: A. L. Muratov & O. Y. Gnedin, 2010, ApJ, 718, 1266 "Modeling the Metallicity Distribution of Globular Clusters"
GMM User Guide (PDF)
Install: Untar the distribution and type make. It will create an executable gmm. Typing make dip will create an executable dip.