Calculating Vedic weekday from Sun and Lagna's longitudes

[Guest guest]

Namaste everyone,

 

I am working on an excel spreadsheet which gives basic planetary calculations

(vargas, dasas, panchaanga etc..) but I am having trouble working out the Vedic

weekday (vaar/vaasara) using the longitudes of the Sun and the Lagna.

 

I thought of using a formula which would return one day less than the Gregorian

weekday if the Sun has a greater longitude than the Lagna but this doesn't work

if for example the Sun is at 1Ar01 and the Lagna is at 29Pi59.

 

Please help me. Thank you very much.