Deterministic annealing expectation

Uses a Euclidean distance metric to determine the distance of each cell from cluster centers, and uses a Gibbs sampler to evaluate the likelihood probability and posterior probability

expectation_step(pca.components, clusters, parameter.estimates, temp,
  num.cores)

Arguments

pca.components	Expects a matrix with n rows as the cells and m columns as the principal components.
clusters	Expect the most likely cluster assignments
parameter.estimates	Expects a list of parameters (mu, covariance, and weights) from initialize_gmm or maximization_step
temp	Current temperature of the algorithm
num.cores	Number of cores used for parallel computation