Calculate the membership matrix according to a set of centroids, the observed data and the fuzziness degree
calcBelongMatrix(centers, data, m, sigmas)
A n * k matrix representing the probability of belonging of each observation to each cluster
A matrix or a dataframe representing the centers of the clusters with p columns and k rows
A dataframe or matrix representing the observed data with n rows and p columns
A float representing the fuzziness degree
A numeric vector for calculating the robust version of the FCM. Filled with ones if the classical version is required