simplify constructor

Author: dance858

src/utils/sparse_matrix.c

@@ -63,13 +63,5 @@ Matrix *new_sparse_matrix(const CSR_Matrix *A)
 Matrix *sparse_matrix_trans(const Sparse_Matrix *self, int *iwork)
 {
     CSR_Matrix *AT = transpose(self->csr, iwork);
-    Sparse_Matrix *sm = (Sparse_Matrix *) calloc(1, sizeof(Sparse_Matrix));
-    sm->base.m = AT->m;
-    sm->base.n = AT->n;
-    sm->base.block_left_mult_vec = sparse_block_left_mult_vec;
-    sm->base.block_left_mult_sparsity = sparse_block_left_mult_sparsity;
-    sm->base.block_left_mult_values = sparse_block_left_mult_values;
-    sm->base.free_fn = sparse_free;
-    sm->csr = AT;
-    return &sm->base;
+    return new_sparse_matrix(AT);
 }