From f5b60e233422c491319fa0c031c445b8a304018e Mon Sep 17 00:00:00 2001
From: =?utf8?q?=C3=98yvind=20A=2E=20Holm?= <sunny@sunbase.org>
Date: Sat, 13 Jul 2013 19:51:04 +0200
Subject: [PATCH] roundgpx: Behave just like gpst, truncate decimals instead of
 rounding

See the famous commit 2349bfd ("gpst: gpst_entry() truncates numbers
instead of rounding", 2013-06-23 19:20:50 +0200) for more information.

10b836dc-ebe5-11e2-a667-001f3b596ec9
---
 roundgpx                          | 16 ++++++++++++----
 tests/roundgpx/files/rounding.gpx |  4 ++--
 tests/roundgpx/roundgpx.t         |  2 +-
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/roundgpx b/roundgpx
index 14a34f4..7a8cf61 100755
--- a/roundgpx
+++ b/roundgpx
@@ -50,11 +50,11 @@ if ($Opt{'version'}) {
 
 while (<>) {
     if (/(.*?<(?:trkpt|rtept|wpt)\s+.*?)"(.*?)"(.*?)"(.*?)"(.*)$/) {
-        my ($num1, $num2) = (sprintf("%.6f", $2), sprintf("%.6f", $4));
-        print("$1\"" . num_expand($num1) . "\"$3\"" . num_expand($num2) . "\"$5\n");
+        my ($num1, $num2) = (trunc_number($2, 6), trunc_number($4, 6));
+        print("$1\"$num1\"$3\"$num2\"$5\n");
     } elsif (/^(.*?<ele>)(-?[\d\.]+)(<\/ele>.*)$/) {
-        my $ele = sprintf("%.3f", $2);
-        print($1 . num_expand($ele) . "$3\n");
+        my $ele = trunc_number($2, 3);
+        print("$1$ele$3\n");
     } else {
         print;
     }
@@ -85,6 +85,14 @@ sub num_expand {
     # }}}
 } # num_expand()
 
+sub trunc_number {
+    # Truncate decimals of floating point number {{{
+    my ($num, $scale) = @_;
+    $num = int($num * (10**$scale)) / 10**$scale;
+    return(num_expand($num));
+    # }}}
+} # trunc_number()
+
 sub print_version {
     # Print program version {{{
     print("$progname v$VERSION\n");
diff --git a/tests/roundgpx/files/rounding.gpx b/tests/roundgpx/files/rounding.gpx
index b18830b..ea7fc86 100644
--- a/tests/roundgpx/files/rounding.gpx
+++ b/tests/roundgpx/files/rounding.gpx
@@ -15,11 +15,11 @@
         <ele>3.00000009</ele>
         <time>2003-02-11T12:17:15Z</time>
       </trkpt>
-      <trkpt lat="51.4837543" lon="-0.0000894">
+      <trkpt lat="51.4837545" lon="-0.0000894">
         <ele>0.00150002</ele>
         <time>2003-02-11T12:17:21Z</time>
       </trkpt>
-      <trkpt lat="51.4836222" lon="0.0000272">
+      <trkpt lat="51.4836229" lon="0.0000279">
         <time>2003-02-11T12:27:41Z</time>
       </trkpt>
     </trkseg>
diff --git a/tests/roundgpx/roundgpx.t b/tests/roundgpx/roundgpx.t
index 17d1840..0b88caf 100755
--- a/tests/roundgpx/roundgpx.t
+++ b/tests/roundgpx/roundgpx.t
@@ -136,7 +136,7 @@ $gpx_header
         <time>2003-02-11T12:17:15Z</time>
       </trkpt>
       <trkpt lat="51.483754" lon="-0.000089">
-        <ele>0.002</ele>
+        <ele>0.001</ele>
         <time>2003-02-11T12:17:21Z</time>
       </trkpt>
       <trkpt lat="51.483622" lon="0.000027">
-- 
2.11.4.GIT