Get classification cost matrix
[COST,LABLIST] = GETCOST(W)
Returns the classification cost matrix as set in the classifier W. An empty cost matrix is interpreted as equal costs for misclassification. In that case COST = ONES(C+1) - EYE(C+1) is returned, if C is the number of classes. Row C+1 and column C+1 in COST refer to unlabeld objects. In LABLIST the class labels are returned. Getcost will return  when no costmatrix is defined.
If A has target labels an error is returned as in that case no classes and thereby no costs are defined.