From 207b28875d0419027482b5ab51671d0272bdb552 Mon Sep 17 00:00:00 2001
From: fred <support@qo-op.com>
Date: Sun, 8 Oct 2023 17:07:21 +0200
Subject: [PATCH] solar time calculator

---
 tools/time2solar.sh | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/tools/time2solar.sh b/tools/time2solar.sh
index b085f528..51ef5e2b 100755
--- a/tools/time2solar.sh
+++ b/tools/time2solar.sh
@@ -1,34 +1,34 @@
 #!/bin/bash
 
 # Input longitude in degrees (positive for East, negative for West)
-longitude_deg=$1
+longitude=$1
+
+# Check if longitude is numeric
+if ! [[ $longitude =~ ^[+-]?[0-9]+(\.[0-9]+)?$ ]]; then
+  echo "Invalid longitude input. Please provide a valid numeric value."
+  exit 1
+fi
 
 # Determine if it's East or West longitude
-if [ $longitude_deg -ge 0 ]; then
+if [ $(echo "$longitude >= 0" | bc) -eq 1 ]; then
   direction="East"
 else
   direction="West"
 fi
 
-# Calculate the time offset in minutes
-offset_minutes=$((longitude_deg * 4))
+# Calculate the time offset in minutes using awk for floating-point arithmetic
+offset_minutes=$(echo "$longitude * 4" | bc)
 
 # Determine if it's ahead or behind UTC
 if [ "$direction" == "West" ]; then
-  offset_minutes=$((offset_minutes * -1))
+  offset_minutes=$(echo "$offset_minutes * -1" | bc)
 fi
 
-# Get the current UTC time in hours, minutes, and seconds
-current_utc_time=$(date -u +%H:%M:%S)
-
-# Convert the UTC time to seconds since midnight
-current_utc_seconds=$(date -u -d "$current_utc_time" +%s)
-
 # Calculate the solar noon time in UTC (12:00 PM)
 solar_noon_utc_seconds=$((12 * 3600))
 
 # Adjust the solar noon time by the offset in seconds
-local_solar_noon_seconds=$((solar_noon_utc_seconds + offset_minutes * 60))
+local_solar_noon_seconds=$(echo "$solar_noon_utc_seconds + ( $offset_minutes * 60 )" | bc | cut -d '.' -f 1)
 
 # Convert the local solar noon time to hours, minutes, and seconds
 local_solar_noon_time=$(date -u -d "@$local_solar_noon_seconds" +%H:%M:%S)
@@ -37,7 +37,7 @@ local_solar_noon_time=$(date -u -d "@$local_solar_noon_seconds" +%H:%M:%S)
 new_time_seconds=$((local_solar_noon_seconds + 8*3600 + 12*60))
 new_time=$(date -u -d "@$new_time_seconds" +%H:%M:%S)
 
-echo "Longitude: $longitude_deg degrees $direction"
+echo "Longitude: $longitude degrees $direction"
 echo "Time Offset: $offset_minutes minutes"
 echo "Local Solar Noon (midday) Time: $local_solar_noon_time"
 echo "Local Solar Noon + 8h 12mn: $new_time"