Respectable Monks, Given 2 points for co-ordinates x and y , I need a function to check if a line is straight ( with some variance), I have the following code which works fine if there is a slope in the line, but if the slope is 0 then I am not sure how to check if the new points are a straight line, here is the code I have , What am I missing here 
sub isCorrectPath () {
                  my ($x1, $y1, $x2, $y2) = @_
                  my $difx =  ($x2 - $x1) ;
                  my $slope = ($difx == 0) ? 0 : ($y2 - $y1) / $difx;
                  return sub  {
                   my ($x, $y) = @_;
                        my $xmin = ($x - $x1);
                        if ( $slope == 0 ) {# if line is straight  
                                if ($difx == 0 )  {# how to make sure 
+the path is correct and in correct direction
                                   
                                        return  (($x - $x1) < 3 ) && (
+(($y - $y1) > 0) || (($y - $y1) > 0));
                                } else {
                                        return  (($y - $y1) < 3 ) && (
+($x - $x1) > 0) || (($x1 - $x) > 0) ;
                                }
                        } else {
                           return  abs(($slope * ($x - $x1)) - ($y - $
+y1)) <= 30;
                        }   
                  } ;        
    }

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In reply to Check if line is straight by Anonymous Monk

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