id my_dtrsm_op(const enum CBLAS_ORDER Order, const enum CBLAS_SIDE Side,
                 const enum CBLAS_UPLO Uplo, const enum CBLAS_TRANSPOSE TransA,
                 const enum CBLAS_DIAG Diag, const int M, const int N,
                 const double alpha, const double *A, const int lda,
                 double *B, const int ldb) {
        int i, j, k;

        for (j = 0; j < N; j++){
                if (alpha){
                        for (i = 0; i < M; i++){
                                B[i * ldb + j] *= alpha;
                        }
                }
                for (k = M - 1; k >= 0; k--){
                        if (B[k * ldb + j]) {
                                B[k * ldb + j] /= A[k * lda + k];
                                for (i = 0; i < k; i++)
                                        B[i * ldb + j] -= B[k * ldb + j] * A[i * lda + j];
                        }
                }

        }
}