Well, unless you have defined your own lt function, you cannot use if (($column_1[$i] gt 10 && lt 50) and ($column_2[$i] gt 100 && lt 200)). It's a syntax error - lt is a binary operator.

A few points, if you know how to test whether something is in the range, you know how to test whether something is outside of the range. Either you are inside, or outside. So to test whether something is outside of the range, just test whether it's not inside the range.

Also, if you are doing numerical compares, you should use the numerical comparison operators: <, <=, ==, >=, > and <=>. gt and lt and friends are for alphabetic compares.

Abigail