code: public static DoubleMatrix absi(DoubleMatrix x) { 
  		/*# mapfct('Math.abs') #*/
  //RJPP-BEGIN------------------------------------------------------------
  	   for (int i = 0; i < x.length; i++)
  	      x.put(i, (double) Math.abs(x.get(i)));
  	   return x;
  //RJPP-END--------------------------------------------------------------
  	}
docs: Sets all elements in this matrix to their absolute values. Note
  that this operation is in-place.
  @see MatrixFunctions#abs(DoubleMatrix)
  @return this matrix