From 68dbd1bd7529414e4bdbd7f41b67f65126991039 Mon Sep 17 00:00:00 2001
From: Brad Cavanagh <b.cavanagh@jach.hawaii.edu>
Date: Thu, 6 Oct 2005 20:04:32 +0000
Subject: [PATCH] when converting from wavelength to filter and using lookup
 table to do so, round the value in the lookup table in the same fashion as
 the rounding of the given wavelength to avoid rounding issues when trying to
 compare floating-point numbers

svn path=/trunk/perlmods/; revision=9403
---
 WaveBand.pm | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/WaveBand.pm b/WaveBand.pm
index ae5a074..22027a8 100644
--- a/WaveBand.pm
+++ b/WaveBand.pm
@@ -102,14 +102,14 @@ my %FILTERS = (
 			   Q =>20.0,
 			  },
 	       WFCAM => {
-			 "Z"     => "0.83",
-			 "Y"     => "0.97",
-			 "J"     => "1.17",
-			 "H"     => "1.49",
-			 "K"     => "2.03",
-			 "1-0S1" => "2.111",
-			 "BGamma"=> "2.155",
-			 "Blank" => "0",
+			 "Z"     => 0.83,
+			 "Y"     => 0.97,
+			 "J"     => 1.17,
+			 "H"     => 1.49,
+			 "K"     => 2.03,
+			 "1-0S1" => 2.111,
+			 "BGamma"=> 2.155,
+			 "Blank" => 0,
 			 },
 	       IRCAM => {
 			 "J98" =>     "1.250" ,
@@ -866,6 +866,7 @@ sub _convert_to {
     # Inverse cm
     $output = 1.0 / ( $lambda / 10_000);
   } elsif ($category eq 'filter') {
+
     # This is slightly harder since we know the value but
     # not the key. Go through each hash looking for a matching
     # key. If we know the instrument we start looking there
@@ -880,16 +881,20 @@ sub _convert_to {
     # the base wavelegnth to use 8 significant figures
     $lambda = sprintf("%8e", $lambda);
 
-    OUTER: foreach my $inst (@search) {
-	next unless exists $FILTERS{$inst};
-	my $hash = $FILTERS{$inst};
-	for my $key (keys %{ $hash }) {
-	  if ($hash->{$key} == $lambda) {
-	    $output = $key;
-	    last OUTER;
-	  }
-	}
+  OUTER: foreach my $inst (@search) {
+      next unless exists $FILTERS{$inst};
+      my $hash = $FILTERS{$inst};
+      for my $key (keys %{ $hash }) {
+        # Make sure we use the same rounding scheme on the values
+        # returned from the hash, so we don't have to worry about
+        # rounding issues fouling things up (like saying 8.3e-1 !=
+        # 0.83).
+        if (sprintf("%8e", $hash->{$key} ) eq $lambda) {
+          $output = $key;
+          last OUTER;
+        }
       }
+    }
   }
 
   return $output;