Compute the the part of the loglikelihood function relevant to omega in step 1
ISOpureS1.model_optimize.omega.omega_loglikelihood(ww, tumordata, model)
(K-1)x1 matrix, log(omega), where the entries in omega are constrained to add to 1 where K-1 is the number of normal samples
a GxD matrix representing gene expression profiles of tumor samples
list containing all the parameters to be optimized
The negative of the loglikelihood function relevant to omega