# HG changeset patch
# User Matti Hamalainen <ccr@tnsp.org>
# Date 1483946585 -7200
# Node ID e28c3347a9480dcd664d60c175890f97282e584f
# Parent  3c816fdc302f9e493a528dc0bd635e7c735e4334
Backed out changeset 3c816fdc302f "great circle distance", for now.

diff -r 3c816fdc302f -r e28c3347a948 weather.tcl
--- a/weather.tcl	Mon Jan 09 05:45:40 2017 +0200
+++ b/weather.tcl	Mon Jan 09 09:23:05 2017 +0200
@@ -327,9 +327,9 @@
     }
 
     # Check argument types
-    set pt1_lat [lindex $nlist 0]
-    set pt1_lng [lindex $nlist 1]
-    if {![string is double -strict $pt1_lat] || ![string is double -strict $pt1_lng]} {
+    set d_lat [lindex $nlist 0]
+    set d_lng [lindex $nlist 1]
+    if {![string is double -strict $d_lat] || ![string is double -strict $d_lng]} {
       weather_msg $upublic $unick $uchan $weather_msg_usage_nearest_invalid
       return 0
     }
@@ -338,27 +338,9 @@
     set result {}
     foreach {ukey uvalue} [array get weather_data] {
       if {![string match "w_*" $ukey]} {
-        set pt2_lat [lindex $uvalue 2]
-        set pt2_lng [lindex $uvalue 3]
-
-        # Calculate "great circle angle" of two lat/long coordinate pairs
-        # https://en.wikipedia.org/wiki/Great-circle_distance
-        #
-        # The result then can be used to calculate approximate distance
-        # between the points when radius of the sphere "R" is known.
-        set d_lng [expr { $pt2_lng - $pt1_lng }]
-        set c_lat1 [expr { cos($pt1_lat) }]
-        set c_lat2 [expr { cos($pt2_lat) }]
-        set s_lat1 [expr { sin($pt1_lat) }]
-        set s_lat2 [expr { sin($pt2_lat) }]
-
-        set f1 [expr { $c_lat2 * sin($d_lng) }]
-        set f2 [expr { $c_lat2 * cos($d_lng) }]
-        set f3 [expr { $c_lat1 * $s_lat2 - $s_lat1 * $f2 }]
-        set c_ang [expr { atan2(sqrt($f1 * $f1 + $f3 * $f3), $s_lat1 * $s_lat2 + $c_lat1 * $f2) }]
-
-        # Calculate distance based on Earth radius approximation in km * 1000m
-        set dist [expr { 6371.439 * 1000.0 * $c_ang }]
+        set delta_lat [expr {$d_lat - [lindex $uvalue 2]}]
+        set delta_lng [expr {$d_lng - [lindex $uvalue 3]}]
+        set dist [expr { sqrt($delta_lat * $delta_lat + $delta_lng * $delta_lng) }]
         lappend result [list $ukey $dist]
       }
     }
@@ -374,7 +356,7 @@
 
     # Print out the result
     set res [join $uresult " ; "]
-    weather_msg $upublic $unick $uchan $weather_msg_nearest_stations [list $pt1_lat $pt1_lng $res]
+    weather_msg $upublic $unick $uchan $weather_msg_nearest_stations [list $d_lat $d_lng $res]
     return 0
   } elseif {$rarg == "vakio" || $rarg == "default" || $rarg == "vakiot" || $rarg == "defaults"} {
     # List or set the default weather station name patterns for this user