Function DMult

Generic matrix-matrix multiplication for block [R:E, S:L] with panel length P. if trans is NOTRANS then calculates C = alpha*A*B + beta*C; C is M*N, A is M*P and B is P*N; if trans is TRANSA then calculates C = alpha*A.T*B + beta*C; C is M*N, A is P*M and B is P*N; if trans is TRANSB then calculate

(C, A, B []float64, alpha, beta float64, trans Flags, ldC, ldA, ldB, P, S, L, R, E, H, NB, MB int)