+ * Adds f to the value at [i, j] and returns the new value
+ *
+ * @param i
+ * @param j
+ * @param f
+ */
+ protected double addValue(int i, int j, double f)
+ {
+ double v = value[i][j] + f;
+ value[i][j] = v;
+ return v;
+ }
+
+ /**
+ * Divides the value at [i, j] by divisor and returns the new value. If d is
+ * zero, returns the unchanged value.
+ *
+ * @param i
+ * @param j
+ * @param divisor
+ * @return
+ */
+ protected double divideValue(int i, int j, double divisor)
+ {
+ if (divisor == 0d)
+ {
+ return getValue(i, j);
+ }
+ double v = value[i][j];
+ v = v / divisor;
+ value[i][j] = v;
+ return v;
+ }
+
+ /**