code: public void setValueAt( int col, int row, double value ) {
          if (makeNew) {
              if (isInRaster(col, row)) {
                  ((WritableRandomIter) iter).setSample(col, row, 0, value);
              } else {
                  throw new RuntimeException("Setting value outside of raster.");
              }
          } else {
              throw new RuntimeException("Writing not allowed.");
          }
      }
docs: Sets a raster value if the raster is writable.
  
  @param col
  @param row
  @param value