Changeset 26186

Timestamp:

Nov 18, 2009, 1:10:03 PM (16 years ago)

Author:

Paul Price

Message:

Fix division by zero.

File:

• trunk/ippScripts/scripts/magic_tree.pl (modified) (2 diffs)

trunk/ippScripts/scripts/magic_tree.pl

@@ -158 +158 @@
 
     # Relative coordinates of centre of the field
-    my $x = $naxis1 - $crpix1;
-    my $y = $naxis2 - $crpix2;
+    my $x = $naxis1/2 - $crpix1;
+    my $y = $naxis2/2 - $crpix2;
 
     # Coordinates on tangent plane
@@ -168 +168 @@
 
     # Coordinates on rotated celestial sphere
-    my $phi = atan2($eta,$xi) + pi/2;
-    my $denominator = sqrt($xi**2 + $eta**2);
-    &my_die("denominator is zero!!", $magic_id, $PS_EXIT_PROG_ERROR) if $denominator == 0;
-
-    my $theta = atan(180 / pi / $denominator);
+    my ($phi, $theta);
+    if ($xi == 0 and $eta == 0) {
+        $phi = 0;
+        $eta = 0;
+    } else {
+        $phi = atan2($eta,$xi) + pi/2;
+        my $denominator = sqrt($xi**2 + $eta**2);
+        &my_die("denominator is zero!!", $magic_id, $PS_EXIT_PROG_ERROR) if $denominator == 0;
+        $theta = atan(180 / pi / $denominator);
+    }
 
     # Coordinates on celestial sphere