I've got many perl scripts in my cgi-bin directory on my ISP's server. This one I cannot get to work -- keep getting and Internal Server Error -- my ISP has no clue.
Permissions are correct 755 for the script.
The path to perl is correct. I've tried it both with the use strict intact and with it commented out.
I don't expect you to debug the script but see if anything jumps out which would cause the typical configuration error -- Internal Server error.
Thanks
Paul
------------ Begin Script ------------
#!/usr/bin/perl -w
# dist -- find great-circle distance between two points on earth's surface
# -*- perl -*-
#
# This code was written in 1998 by Darrell Kindred <dkindred@cmu.edu>.
# I have released it into the public domain. Do what you like with it,
# but if you make any modifications, please either list your name and
# describe the changes here, or remove my name and address above.
#
# This code is distributed without any warranty, express or implied.
#
# Calculate the great-circle distance and initial heading from one point on
# the Earth to another, given latitude & longitude.
# usage: dist <location1> <location2>
#
# Calculations assume a spherical Earth with radius 6367 km.
# (I think this should cause no more than 0.2% error.)
#
# Here are some examples of acceptable location formats:
#
# 40:26:46N,79:56:55W
# 40:26:46.302N 79:56:55.903W
# 40°26'21"N 79d58'36"W
# 40d 26' 21" N 79d 58' 36" W
# 40.446195N 79.948862W
# 40.446195N -79.948862E
#
# Be sure to quote arguments from the shell as necessary.
#
# For a good discussion of the formula used here for calculating distances,
# as well as several more and less accurate techniques, see
# http://www.census.gov/cgi-bin/geo/gisfaq?Q5.1
# and
# http://www.best.com/~williams/avform.htm
require 5.001;
use strict;
if (scalar(@ARGV) == 2) {
my($lat1,$long1) = &parse_location(shift);
my($lat2,$long2) = &parse_location(shift);
my $meters_per_mile = 1609.344;
my $nautical_miles_per_mile = (5280 / 6076);
my $dist = &great_circle_distance($lat1,$long1,$lat2,$long2);
my $heading = &radians_to_degrees(&initial_heading($lat1,$long1,
$lat2,$long2));
print "great-circle distance from ", &loc_to_string($lat1,$long1), " to ",
&loc_to_string($lat2,$long2), " is\n";
# round to 3 significant digits since that's all we are justified
# in printing given the spherical earth assumption.
printf("%8g km\n", &round_to_3($dist / 1000));
printf("%8g miles\n", &round_to_3($dist / $meters_per_mile));
printf("%8g nautical miles\n",
&round_to_3($dist / $meters_per_mile * $nautical_miles_per_mile));
printf("initial heading: %.0f degrees (%s)\n",
$heading, &heading_string($heading));
} else {
print STDERR "$0: two arguments required, ", scalar(@ARGV), " found\n";
print STDERR "usage: $0 <loc1> <loc2>\n";
print STDERR " allowed loc formats: \n";
print STDERR <<\EndFormats;
40:26:46N,79:56:55W
40:26:46.302N 79:56:55.903W
40°26'21"N 79d58'36"W
40d 26' 21" N 79d 58' 36" W
40.446195N 79.948862W
40.446195N -79.948862E
EndFormats
exit(1);
}
# given coordinates of two places in radians, compute distance in meters
sub great_circle_distance {
my ($lat1,$long1,$lat2,$long2) = @_;
# approx radius of Earth in meters. True radius varies from
# 6357km (polar) to 6378km (equatorial).
my $earth_radius = 6367000;
my $dlon = $long2 - $long1;
my $dlat = $lat2 - $lat1;
my $a = (sin($dlat / 2)) ** 2
+ cos($lat1) * cos($lat2) * (sin($dlon / 2)) ** 2;
my $d = 2 * atan2(sqrt($a), sqrt(1 - $a));
# This is a simpler formula, but it's subject to rounding errors
# for small distances. See http://www.census.gov/cgi-bin/geo/gisfaq?Q5.1
# my $d = &acos(sin($lat1) * sin($lat2)
# + cos($lat1) * cos($lat2) * cos($long1-$long2));
return $earth_radius * $d;
}
# compute the initial bearing (in radians) to get from lat1/long1 to lat2/long2
sub initial_heading {
my ($lat1,$long1,$lat2,$long2) = @_;
BEGIN {
$::pi = 4 * atan2(1,1);
}
# note that this is the same $d calculation as above.
# duplicated for clarity.
my $dlon = $long2 - $long1;
my $dlat = $lat2 - $lat1;
my $a = (sin($dlat / 2)) ** 2
+ cos($lat1) * cos($lat2) * (sin($dlon / 2)) ** 2;
my $d = 2 * atan2(sqrt($a), sqrt(1 - $a));
my $heading = acos((sin($lat2) - sin($lat1) * cos($d))
/ (sin($d) * cos($lat1)));
if (sin($long2 - $long1) < 0) {
$heading = 2 * $::pi - $heading;
}
return $heading;
}
# return an angle in radians, between 0 and pi, whose cosine is x
sub acos {
my($x) = @_;
die "bad acos argument ($x)\n" if (abs($x) > 1.0);
return atan2(sqrt(1 - $x * $x), $x);
}
# round to 3 significant digits
sub round_to_3 {
my ($num) = @_;
my ($lg,$round);
if ($num == 0) {
return 0;
}
$lg = int(log(abs($num)) / log(10.0)); # log base 10 of num
$round = 10 ** ($lg - 2);
return int($num / $round + 0.5) * $round;
}
# round to nearest integer
sub round_to_int {
return int(abs($_[0]) + 0.5) * ($_[0] < 0 ? -1 : 1);
}
# print a location in a canonical form
sub loc_to_string {
my($lat,$long) = @_;
$lat = &radians_to_degrees($lat);
$long = &radians_to_degrees($long);
my $ns = "N";
my $ew = "E";
if ($lat < 0) {
$lat = -$lat;
$ns = "S";
}
if ($long < 0) {
$long = -$long;
$ew = "W";
}
$lat = int($lat * 3600 + 0.5);
my $lat_string = sprintf("%d:%02d:%02d%s",
int($lat/3600),
int(($lat - 3600*int($lat / 3600))/60),
$lat - 60*int($lat / 60),
$ns);
$long = int($long * 3600 + 0.5);
my $long_string = sprintf("%d:%02d:%02d%s",
int($long/3600),
int(($long - 3600*int($long / 3600))/60),
$long - 60*int($long / 60),
$ew);
return "$lat_string $long_string";
}
# convert a string which looks like "34:45:12N,15:34:10W" into a pair
# of degrees. Also accepts "34.233N,90.134E" etc.
sub parse_location {
my($str) = @_;
my($lat,$long);
if ($str =~ /^([0-9:.\260'"d -]*)([NS])[, ]+([0-9:.\260'"d -]*)([EW])$/i) {
return undef if (!defined($lat = &parse_degrees($1)));
$lat *= (($2 eq "N" | | $2 eq "n") ? 1.0 : -1.0);
return undef if (!defined($long = &parse_degrees($3)));
$long *= (($4 eq "E" | | $4 eq "e") ? 1.0 : -1.0);
return(°rees_to_radians($lat), °rees_to_radians($long));
} else {
return undef;
}
}
# given a bearing in degrees, return a string "north", "southwest",
# "east-southeast", etc.
sub heading_string {
my($deg) = @_;
my($rounded,$s);
my(@dirs) = ("north","east","south","west");
$rounded = &round_to_int($deg / 22.5) % 16;
if (($rounded % 4) == 0) {
$s = $dirs[$rounded/4];
} else {
$s = $dirs[2 * int(((int($rounded / 4) + 1) % 4) / 2)];
$s .= $dirs[1 + 2 * int($rounded / 8)];
if ($rounded % 2 == 1) {
$s = $dirs[&round_to_int($rounded/4) % 4] . "-" . $s;
}
}
return $s;
}
BEGIN { $::pi = 4 * atan2(1,1); }
sub degrees_to_radians {
return $_[0] * $::pi / 180.0;
}
sub radians_to_degrees {
return $_[0] * 180.0 / $::pi;
}
# convert a string like 34:45:12.34 or 38:40 or 34.124 or 34d45'12.34"
# or 25° 02' 30" to degrees
# (also handles a leading `-')
sub parse_degrees {
my($str) = @_;
my($d,$m,$s,$sign);
# yeah, this could probably be done with one regexp.
if ($str =~ /^\s*(-?)([\d.]+)\s*(:|d|\260)\s*([\d.]+)\s*(:|\')\s*([\d.]+)\s*\"?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = $4 + 0.0;
$s = $6 + 0.0;
} elsif ($str =~ /^\s*(-?)([\d.]+)\s*(:|d|\260)\s*([\d.]+)(\')?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = $4 + 0.0;
$s = 0.0;
} elsif ($str =~ /^\s*(-?)([\d.]+)(d|\260)?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = 0.0;
$s = 0.0;
} else {
die "parse_degrees: can't parse $str\n";
}
return ($sign * ($d + ($m / 60.0) + ($s / 3600.0)));
}
Permissions are correct 755 for the script.
The path to perl is correct. I've tried it both with the use strict intact and with it commented out.
I don't expect you to debug the script but see if anything jumps out which would cause the typical configuration error -- Internal Server error.
Thanks
Paul
------------ Begin Script ------------
#!/usr/bin/perl -w
# dist -- find great-circle distance between two points on earth's surface
# -*- perl -*-
#
# This code was written in 1998 by Darrell Kindred <dkindred@cmu.edu>.
# I have released it into the public domain. Do what you like with it,
# but if you make any modifications, please either list your name and
# describe the changes here, or remove my name and address above.
#
# This code is distributed without any warranty, express or implied.
#
# Calculate the great-circle distance and initial heading from one point on
# the Earth to another, given latitude & longitude.
# usage: dist <location1> <location2>
#
# Calculations assume a spherical Earth with radius 6367 km.
# (I think this should cause no more than 0.2% error.)
#
# Here are some examples of acceptable location formats:
#
# 40:26:46N,79:56:55W
# 40:26:46.302N 79:56:55.903W
# 40°26'21"N 79d58'36"W
# 40d 26' 21" N 79d 58' 36" W
# 40.446195N 79.948862W
# 40.446195N -79.948862E
#
# Be sure to quote arguments from the shell as necessary.
#
# For a good discussion of the formula used here for calculating distances,
# as well as several more and less accurate techniques, see
# http://www.census.gov/cgi-bin/geo/gisfaq?Q5.1
# and
# http://www.best.com/~williams/avform.htm
require 5.001;
use strict;
if (scalar(@ARGV) == 2) {
my($lat1,$long1) = &parse_location(shift);
my($lat2,$long2) = &parse_location(shift);
my $meters_per_mile = 1609.344;
my $nautical_miles_per_mile = (5280 / 6076);
my $dist = &great_circle_distance($lat1,$long1,$lat2,$long2);
my $heading = &radians_to_degrees(&initial_heading($lat1,$long1,
$lat2,$long2));
print "great-circle distance from ", &loc_to_string($lat1,$long1), " to ",
&loc_to_string($lat2,$long2), " is\n";
# round to 3 significant digits since that's all we are justified
# in printing given the spherical earth assumption.
printf("%8g km\n", &round_to_3($dist / 1000));
printf("%8g miles\n", &round_to_3($dist / $meters_per_mile));
printf("%8g nautical miles\n",
&round_to_3($dist / $meters_per_mile * $nautical_miles_per_mile));
printf("initial heading: %.0f degrees (%s)\n",
$heading, &heading_string($heading));
} else {
print STDERR "$0: two arguments required, ", scalar(@ARGV), " found\n";
print STDERR "usage: $0 <loc1> <loc2>\n";
print STDERR " allowed loc formats: \n";
print STDERR <<\EndFormats;
40:26:46N,79:56:55W
40:26:46.302N 79:56:55.903W
40°26'21"N 79d58'36"W
40d 26' 21" N 79d 58' 36" W
40.446195N 79.948862W
40.446195N -79.948862E
EndFormats
exit(1);
}
# given coordinates of two places in radians, compute distance in meters
sub great_circle_distance {
my ($lat1,$long1,$lat2,$long2) = @_;
# approx radius of Earth in meters. True radius varies from
# 6357km (polar) to 6378km (equatorial).
my $earth_radius = 6367000;
my $dlon = $long2 - $long1;
my $dlat = $lat2 - $lat1;
my $a = (sin($dlat / 2)) ** 2
+ cos($lat1) * cos($lat2) * (sin($dlon / 2)) ** 2;
my $d = 2 * atan2(sqrt($a), sqrt(1 - $a));
# This is a simpler formula, but it's subject to rounding errors
# for small distances. See http://www.census.gov/cgi-bin/geo/gisfaq?Q5.1
# my $d = &acos(sin($lat1) * sin($lat2)
# + cos($lat1) * cos($lat2) * cos($long1-$long2));
return $earth_radius * $d;
}
# compute the initial bearing (in radians) to get from lat1/long1 to lat2/long2
sub initial_heading {
my ($lat1,$long1,$lat2,$long2) = @_;
BEGIN {
$::pi = 4 * atan2(1,1);
}
# note that this is the same $d calculation as above.
# duplicated for clarity.
my $dlon = $long2 - $long1;
my $dlat = $lat2 - $lat1;
my $a = (sin($dlat / 2)) ** 2
+ cos($lat1) * cos($lat2) * (sin($dlon / 2)) ** 2;
my $d = 2 * atan2(sqrt($a), sqrt(1 - $a));
my $heading = acos((sin($lat2) - sin($lat1) * cos($d))
/ (sin($d) * cos($lat1)));
if (sin($long2 - $long1) < 0) {
$heading = 2 * $::pi - $heading;
}
return $heading;
}
# return an angle in radians, between 0 and pi, whose cosine is x
sub acos {
my($x) = @_;
die "bad acos argument ($x)\n" if (abs($x) > 1.0);
return atan2(sqrt(1 - $x * $x), $x);
}
# round to 3 significant digits
sub round_to_3 {
my ($num) = @_;
my ($lg,$round);
if ($num == 0) {
return 0;
}
$lg = int(log(abs($num)) / log(10.0)); # log base 10 of num
$round = 10 ** ($lg - 2);
return int($num / $round + 0.5) * $round;
}
# round to nearest integer
sub round_to_int {
return int(abs($_[0]) + 0.5) * ($_[0] < 0 ? -1 : 1);
}
# print a location in a canonical form
sub loc_to_string {
my($lat,$long) = @_;
$lat = &radians_to_degrees($lat);
$long = &radians_to_degrees($long);
my $ns = "N";
my $ew = "E";
if ($lat < 0) {
$lat = -$lat;
$ns = "S";
}
if ($long < 0) {
$long = -$long;
$ew = "W";
}
$lat = int($lat * 3600 + 0.5);
my $lat_string = sprintf("%d:%02d:%02d%s",
int($lat/3600),
int(($lat - 3600*int($lat / 3600))/60),
$lat - 60*int($lat / 60),
$ns);
$long = int($long * 3600 + 0.5);
my $long_string = sprintf("%d:%02d:%02d%s",
int($long/3600),
int(($long - 3600*int($long / 3600))/60),
$long - 60*int($long / 60),
$ew);
return "$lat_string $long_string";
}
# convert a string which looks like "34:45:12N,15:34:10W" into a pair
# of degrees. Also accepts "34.233N,90.134E" etc.
sub parse_location {
my($str) = @_;
my($lat,$long);
if ($str =~ /^([0-9:.\260'"d -]*)([NS])[, ]+([0-9:.\260'"d -]*)([EW])$/i) {
return undef if (!defined($lat = &parse_degrees($1)));
$lat *= (($2 eq "N" | | $2 eq "n") ? 1.0 : -1.0);
return undef if (!defined($long = &parse_degrees($3)));
$long *= (($4 eq "E" | | $4 eq "e") ? 1.0 : -1.0);
return(°rees_to_radians($lat), °rees_to_radians($long));
} else {
return undef;
}
}
# given a bearing in degrees, return a string "north", "southwest",
# "east-southeast", etc.
sub heading_string {
my($deg) = @_;
my($rounded,$s);
my(@dirs) = ("north","east","south","west");
$rounded = &round_to_int($deg / 22.5) % 16;
if (($rounded % 4) == 0) {
$s = $dirs[$rounded/4];
} else {
$s = $dirs[2 * int(((int($rounded / 4) + 1) % 4) / 2)];
$s .= $dirs[1 + 2 * int($rounded / 8)];
if ($rounded % 2 == 1) {
$s = $dirs[&round_to_int($rounded/4) % 4] . "-" . $s;
}
}
return $s;
}
BEGIN { $::pi = 4 * atan2(1,1); }
sub degrees_to_radians {
return $_[0] * $::pi / 180.0;
}
sub radians_to_degrees {
return $_[0] * 180.0 / $::pi;
}
# convert a string like 34:45:12.34 or 38:40 or 34.124 or 34d45'12.34"
# or 25° 02' 30" to degrees
# (also handles a leading `-')
sub parse_degrees {
my($str) = @_;
my($d,$m,$s,$sign);
# yeah, this could probably be done with one regexp.
if ($str =~ /^\s*(-?)([\d.]+)\s*(:|d|\260)\s*([\d.]+)\s*(:|\')\s*([\d.]+)\s*\"?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = $4 + 0.0;
$s = $6 + 0.0;
} elsif ($str =~ /^\s*(-?)([\d.]+)\s*(:|d|\260)\s*([\d.]+)(\')?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = $4 + 0.0;
$s = 0.0;
} elsif ($str =~ /^\s*(-?)([\d.]+)(d|\260)?\s*$/) {
$sign = ($1 eq "-") ? -1.0 : 1.0;
$d = $2 + 0.0;
$m = 0.0;
$s = 0.0;
} else {
die "parse_degrees: can't parse $str\n";
}
return ($sign * ($d + ($m / 60.0) + ($s / 3600.0)));
}