perlquestion hacker I've been working with [http://gnu-designs.com/code/zipcrunch.c|some C code] that crunches the [http://www.census.gov/geo/ZCTA/zcta.html|2000 US Census data] into CSV files, based on the specified proximity to the origin zipcode. The problem is that the C code is horribly slow, and I can't seem to figure out why. It takes my PIII/1.3Ghz/512mb RAM machine about 20 minutes to crunch the 987k input data file for zipcodes matching within a 0-25 radius of the givin origin zipcode. That seems very slow. <p>The master 2000 Census data file contains records in this format:<code> ZIP_CODE ONGITUD ATITUD 00210 71.0132 43.00589 00211 71.0132 43.00589 00212 71.0132 43.00589 00213 71.0132 43.00589 00214 71.0132 43.00589 00215 71.0132 43.00589 ...</code> <p>My output file, separate for each type of range (0-25.txt for zipcodes within 0-25 miles of the origin, 0-50.txt for zipcodes within 0-50 miles of the origin, etc.), contains entries such as:<code> 00210,00210 00210,00211 00211,00210 00210,00212 00212,00210 00210,00213 ...</code> <p>For each given zipcode found in the master file (where <i>origin</i> == 00210 in this case, to start with), I want to output a file that contains all matching zipcodes within the specified proximity to that zipcode. So in the example above, all of the zipcodes within 0-25 miles of 00210 would be output to 0-25.txt, a csv file containing the data shown above. <p>I have the working radii functions which do this, and does work (but is very slow), and looks like: <code> #define EARTH_RADIUS 3956 static inline float deg_to_rad(float deg) { return (deg * M_PI / 180.0); } /* Function to calculate Great Circle distance between two points. */ static inline float great_circle_distance(float lat1, float long1, float lat2, float long2) { float delta_long, delta_lat, temp, distance; /* Find the deltas */ delta_lat = lat2 - lat1; delta_long = long2 - long1; /* Find the GC distance */ temp = pow(sin(delta_lat / 2.0), 2) + cos(lat1) * cos(lat2) * pow(sin(delta_long / 2.0), 2); distance = EARTH_RADIUS * 2 * atan2(sqrt(temp), sqrt(1 - temp)); return (distance); }</code> <p>In perl, this would be:<code> my $distance = sqrt(($x1-$x2)**2+($y1-$y2)**2);</code> <p>My goal is to convert this over to perl, both so I can gain the speed and efficiency of perl (as well as make this portable to Windows systems, where the current C code doesn't quite run yet), as well as expand my knowledge of perl in general. <p>Has anyone done this? Any pointers that might be useful here?