public FloatColumn neg(){
  FloatColumn newColumn=FloatColumn.create(name() + "[neg]",size());
  for (  float value : this) {
    newColumn.add(value * -1);
  }
  return newColumn;
}

public FloatColumn neg ( ) { FloatColumn newColumn = FloatColumn . create ( name ( ) + "[neg]" , size ( ) ) ; for ( float value : this ) { newColumn . add ( value * - 1 ) ; } return newColumn ; }
for each item in the column , returns the same number with the sign changed . for example : - 1 . 3 returns 1 . 3 , 2 . 135 returns - 2 . 135 0 returns 0
