Re: fastest way to compare numerical strings?

[grep]

Just a quick note:

The take the abs value of the difference between the 2 numbers, check if that is greater than .01. That should read cleaner and get rid of most of those checks.

Also as a favor for the people trying to read your code - pick a style of indenting.

#untested
for ($n=0;$n<=$#lat;$n++) {
    for ($v=0;$v<=$#lat;$v++) {
        if ( abs( $lat[$n] - $lat[$v] ) < .01 and abs( $long[$n] -  $l
+ong[$v] ) < .01 )  {
            ##OTHER CODE   
        }
    }
}

Update: fixed typo and minor edit