2 files changed, 3 insertions, 3 deletions
diff --git a/matrix.c b/matrix.c
index a784308..9992bfb 100644
--- a/matrix.c
+++ b/matrix.c
@@ -206,7 +206,7 @@ Matrix *matrix_add(const Matrix *A, const Matrix *B)
     return C;
 }
 
-Matrix *matrix_scale(double x, const Matrix *A)
+Matrix *matrix_scale(const Matrix *A, double x)
 {
     Matrix *tmp = matrix_alloc(A->m, A->n);
 
@@ -221,7 +221,7 @@ Matrix *matrix_scale(double x, const Matrix *A)
 
 Matrix *matrix_sub(const Matrix *A, const Matrix *B)
 {
-    return matrix_add(A, matrix_scale(-1, B));
+    return matrix_add(A, matrix_scale(B, -1));
 }
 
 Matrix *matrix_mult(const Matrix *A, const Matrix *B)
diff --git a/matrix.h b/matrix.h
index aa95771..5ee5dc3 100644
--- a/matrix.h
+++ b/matrix.h
@@ -42,7 +42,7 @@ void matrix_swap1(Matrix *mat, MatrixSwapType t, size_t i, size_t j);
 double matrix_trace(const Matrix *mat);
 Matrix *matrix_transpose(const Matrix *mat);
 Matrix *matrix_add(const Matrix *A, const Matrix *B);
-Matrix *matrix_scale(double x, const Matrix *A);
+Matrix *matrix_scale(const Matrix *A, double x);
 Matrix *matrix_sub(const Matrix *A, const Matrix *B);
 Matrix *matrix_mult(const Matrix *A, const Matrix *B);
 Matrix *matrix_rand(size_t m, size_t n, int bound_l, int bound_u, MatrixType type);