Finding the Borders of a Campanus Houses

Hi Ernst,
hi all,

for different reasons I want to calculate the beginnings and endings (borders) of the campanus-houses in a chart.

Kala and swissephemeris ( https://www.astro.com/swisseph/swetest.html) give the house cusps, but not the beginning and starting points. 

When I simply add half of the difference between the cusps to the house cusp the borders between the houses do not line up. Either they overlap or there is a gap between the end of one house and the next.

If I simple set the end of one house as the starting point of the next (as jagannatha hora seems to do), without bothering with the mathematical results the two halves (poorva and uttara bhaga) of the house are unequally big.

but having the house cusp in the MIDDLE of the house in a vedic chart means that the way from the house cusp to the starting and endpoint has to be equal, right? I mean, middle means verbatim right in the middle and not somewhere in the house - compared to western astrolgy where the cusp usually defines the beginning of the house, right?  (by the way I am not sure if this has to be the case for ALL the houses or only for the lagna?)

If I take half the difference between the next higher and next lower cusp (for example 12th HC-1st HC and 2nd HC-1st HC), the upper and lower half of the houses are perfectly equal, but again the borders don't fit.

Any clue how to do the calculation right? As I am not a programmer I have to rely on excel and similar.

thank you in advance!

christian