seems to work.

Projekt1_Knuettel_Daniel.c

@@ -34,9 +34,21 @@
 /*
  * General Information:
  *
- * - Matrices are represented using line vectors. This is
+ * - Matrices are represented using row vectors. This is
  *   convenient for accessing elements.
  *
+ * Compiling:
+ *
+ * Use
+ *
+ * 	gcc -lm -o main Projekt1_Knuettel_Daniel.c
+ *
+ * To produce the executable. You can use
+ *
+ * 	gcc -DDEBUG -g -lm -o main Projekt1_Knuettel_Daniel.c
+ *
+ * To enable a rudimentary debug mode. 
+ *
  * */
 
 #include <stdio.h>
@@ -243,6 +255,10 @@ int main(void)
 		A_2[i] = malloc(sizeof(double) * n);
 		for(j = 0; j < n; j++)
 		{
+#ifdef DEBUG
+			fprintf(stderr, "set A_2[%d][%d] = A_stack_2[%d] = %f\n"
+					, i, j, n*i + j, A_stack_2[n*i + j]);
+#endif
 			A_2[i][j] = A_stack_2[n*i + j];
 		}
 	}
@@ -330,7 +346,9 @@ int householder(double ** A, double * alpha, int m, int n)
 	 * This is just the sample implementation from the 
 	 * lecture script.
 	 * */
-	for(k = 0; k < min(n, m - 1); k++)
+	// I figured out that min(n, m - 1) from the scrip is wrong.
+	// It must be because the last row would be uninitialized.
+	for(k = 0; k < min(n, m); k++)
 	{
 		alpha[k] = square(A[k][k]);