Fixed all matrix.c, all tests passed

Startcode/matrix.c

@@ -25,7 +25,7 @@ void clearMatrix(Matrix *matrix)
 void setMatrixAt(MatrixType value, Matrix matrix, unsigned int rowIdx, unsigned int colIdx)
 {
     if(rowIdx < matrix.rows && colIdx < matrix.cols){
-        *(matrix.buffer + rowIdx * matrix.rows + colIdx) = value;
+        *(matrix.buffer + rowIdx * matrix.cols + colIdx) = value;
     }
 }
 
@@ -34,7 +34,7 @@ MatrixType getMatrixAt(const Matrix matrix, unsigned int rowIdx, unsigned int co
     if(rowIdx >= matrix.rows || colIdx >= matrix.cols){
         return 0;
     }
-    return *(matrix.buffer + rowIdx * matrix.rows + colIdx);
+    return *(matrix.buffer + rowIdx * matrix.cols + colIdx);
 }
 
 Matrix add(const Matrix matrix1, const Matrix matrix2)
@@ -42,7 +42,7 @@ Matrix add(const Matrix matrix1, const Matrix matrix2)
     int n1 = matrix1.cols;
     int m1 = matrix1.rows;
     int n2 = matrix2.cols;
-    int m2 = matrix2.cols;
+    int m2 = matrix2.rows;
 
     if(n1 == 1 && m1 == m2){
         Matrix new_mat = createMatrix(m2, n2);
@@ -68,7 +68,7 @@ Matrix add(const Matrix matrix1, const Matrix matrix2)
         return (Matrix) {0, 0, NULL};
     }
 
-    Matrix new_mat = createMatrix(n1, m1);
+    Matrix new_mat = createMatrix(m1, n1);
 
     for(int i = 0; i < m1; i++){
         for(int j = 0; j < n1; j++){