matrix multiplication of two matrices
[sim,out] = ld_matmul(sim, events, left_matrix, left_matrix_size, right_matrix, right_matrix_size)
out = left_matrix * right_matrix
left_matrix *+(left_matrix_size) - matrix signal
left_matrix_size ---> matrix size [nr,nc]
right_matrix *+(right_matrix_size) - matrix signal
right_matrix_size ---> matrix size [nr,nc]