Function: minus(gradient[1](numbers("xxy") if square(numbers("xxy")) > numbers('epe') else numbers('xyy') if square(numbers("xxy")) > numbers('epe') else numbers("xxy")), square(numbers("xxy")) if numbers('epe') > numbers("xxy") else square(numbers("xxy")) if numbers("xxy") > numbers('xyy') else numbers('epe'))
