diff --git a/assignment-2a/src/HW2a.cpp b/assignment-2a/src/HW2a.cpp
index 703b2e7..9eb4dc6 100755
--- a/assignment-2a/src/HW2a.cpp
+++ b/assignment-2a/src/HW2a.cpp
@@ -117,6 +117,12 @@ key_callback(GLFWwindow *window, int key, int scancode, int action, int mods) {
 
     else if (key == GLFW_KEY_DOWN || key == GLFW_KEY_S)
       scale_y -= SCALE_DELTA;
+
+    if (scale_x <= 0)
+      scale_x = SCALE_DELTA;
+
+    if (scale_y <= 0)
+      scale_y = SCALE_DELTA;
   }
 }
 
@@ -298,7 +304,8 @@ int main(int argc, char **argv) {
     // be the identity matrix; you will need define M according to the user's
     // actions.
 
-    slow4x4MatrixMultiplyIntoColumnOrder(rotation_matrix, scale_matrix, M);
+    slow4x4MatrixMultiplyAllRowOrder(rotation_matrix, scale_matrix, M);
+    transposeMatrix(M);
 
     // sanity check that your matrix contents are what you expect them to be
     if (DEBUG_ON) {
@@ -346,7 +353,15 @@ void printMatrix(string name, GLfloat *matrix) {
   );
 }
 
-void transposeMatrix(GLfloat *matrix) {}
+void transposeMatrix(GLfloat *matrix) {
+  for (int i = 0; i < 4; ++i) {
+    for (int j = i + 1; j < 4; ++j) {
+      GLfloat tmp = matrix[i * 4 + j];
+      matrix[i * 4 + j] = matrix[j * 4 + i];
+      matrix[j * 4 + i] = tmp;
+    }
+  }
+}
 
 void zeroInitGlfloats(GLfloat *arr, uint32_t len) {
   for (auto i = 0; i < len; ++i) {
@@ -354,29 +369,16 @@ void zeroInitGlfloats(GLfloat *arr, uint32_t len) {
   }
 }
 
-void slow4x4MatrixMultiplyIntoColumnOrder(
-    GLfloat *left, GLfloat *right, GLfloat *result
-) {
-  for (int i = 0; i < 4; ++i) {
-    for (int j = 0; j < 4; ++j) {
-      for (int k = 0; k < 4; ++k) {
-        const GLfloat leftVal = left[i * 4 + k];
-        const GLfloat rightVal = right[j * 4 + k];
-        result[j * 4 + i] += leftVal * rightVal;
-      }
-    }
-  }
-}
-
 void slow4x4MatrixMultiplyAllRowOrder(
     GLfloat *left, GLfloat *right, GLfloat *result
 ) {
   for (int i = 0; i < 4; ++i) {
     for (int j = 0; j < 4; ++j) {
+      result[i * 4 + j] = 0;
       for (int k = 0; k < 4; ++k) {
         const GLfloat leftVal = left[i * 4 + k];
-        const GLfloat rightVal = right[j * 4 + k];
-        result[j * 4 + i] += leftVal * rightVal;
+        const GLfloat rightVal = right[k + j * 4];
+        result[i * 4 + j] += leftVal * rightVal;
       }
     }
   }