diff --git a/info2praktikum-neuronalesnetz/matrix.c b/info2praktikum-neuronalesnetz/matrix.c
index 75c311b..af5a474 100644
--- a/info2praktikum-neuronalesnetz/matrix.c
+++ b/info2praktikum-neuronalesnetz/matrix.c
@@ -34,7 +34,12 @@ void setMatrixAt(MatrixType value, Matrix matrix, unsigned int rowIdx, unsigned
 
 MatrixType getMatrixAt(const Matrix matrix, unsigned int rowIdx, unsigned int colIdx)
 {
-    
+    if(rowIdx > matrix.rows || colIdx > matrix.cols){
+      return 0;
+      }
+    MatrixType value;
+    value = matrix.data[rowIdx * matrix.cols + colIdx];
+    return value;
 }
 
 Matrix add(const Matrix matrix1, const Matrix matrix2)
@@ -44,7 +49,24 @@ Matrix add(const Matrix matrix1, const Matrix matrix2)
 
 Matrix multiply(const Matrix matrix1, const Matrix matrix2)
 {
-    
+    if (matrix1.cols != matrix2.rows){
+      Matrix errorMatrix = createMatrix(0, 0);
+      errorMatrix.data = NULL;
+      return errorMatrix;
+      }
+    Matrix matrix3 = createMatrix(matrix1.rows, matrix2.cols);
+
+    for( size_t i = 0; i < matrix1.rows; i++){
+      for(size_t j = 0; j < matrix2.cols; j++){
+        MatrixType sum = 0;
+        for(size_t k = 0; k < matrix1.cols; k++){
+          sum += getMatrixAt(matrix1, i, k) * getMatrixAt(matrix2, k, j);
+        }
+        setMatrixAt(sum, matrix3, i, j);
+      }
+    }
+
+    return matrix3;
 }