very useful function need to be reversed

this function calculates the maximum down correction between 2 points

could any one please reverse it,, to calculate the maximum up correction

double getDif(int X0, int X3 )
{
   double maxdif;
   int P,B;
   for(int i=MathMax(X0,X3); i>=MathMin(X0,X3); i--)
   {
      for(int p=i-1; p>=MathMin(X0,X3); p--)
      {
         if(High[i]-Low[p] > maxdif )
         {
            maxdif = High[i]-Low[p];
            P = i;
            B = p;
         }
      }
   }
   
   

   
   CorrB = MathAbs(P-B); 
   
   return(NormalizeDouble(maxdif/Point,0));
}