subtract decimal degrees (longitude readings) in php

Question

In PHP, how to subtract $Longitude_1 = 72.8790721063599 from $Longitude_2 = 82.22? These are decimal degree values from Google geocoding.

I need to find the difference and convert it into time.

The time value comes close to 40 minutes as I know in this case.

Also, 1 Degree = 4 mins and not 60 mins when it comes to time differences from longitudinal positions. So if I have the coordinate difference in degrees, I can convert the same to time units. It is to get to the Local Mean Time at the concerned longitude!

Answer 1

Addressing what I see to be your core questions here:

Well, how do you get the difference of values which are in DD format?

$Longitude_2 = 82.22;
$Longitude_1 = 72.8790721063599;

//get the difference
$diff = $Longitude_2 - $Longitude_1; //9.3409278936401

and then convert the values to Degrees so that time can be obtained in the end.

Your answer, stored in $diff, is already in decimal degrees, so there's nothing to convert. Per your source, 1 degree = 4 minutes time, so simply multiply:

//get the time value
$diff_time = $diff * 4; //37.3637115745604

So, the actual time value is close to 37 minutes for your particular case.