In a prior blog post, Is it Normal?, we began with two normal distributions and summed their frequencies to obtain a Gaussian mixture. In this post, we begin with a Gaussian mixture and deploy the Expectation-Maximization (EM) algorithm to decompose a given Gaussian mixture into its component distributions. Example code is included, and the results of these examples are contrasted with that of an R package mixtools, a professional software release which is based upon based upon work supported by the National Science Foundation under Grant No.