While in H temple architecture there is a strong tendency to use to n mod 4 = 0 there are occasional examples of the "inconstructible" (i.e. by yavana constraints) polygons in H temples. Below is a great example which was consciously chosen for a viShNu temple because the
trayodashAra-chakra, i.e. the inner chakra represents the 13 months of the saMvatsara: 12 regular months+ 1 intercalary month. This is already mentioned by shunaHshepa Ajigarti in the RV:
veda mAso dhR^itavrato dvAdasha prajAvataH |
vedA ya upajAyate ||
veda mAso dhR^itavrato dvAdasha prajAvataH |
vedA ya upajAyate ||
He [वरुणः] whose laws are upheld knows the 12 months and their offspring [ardhamAsa-s].
He knows the one that is born afterward (the 13th or intercalary month) in the saMvatsara. Now why are there 29 in the outer chakra? That is the rounded off duration of the synodic month i.e
He knows the one that is born afterward (the 13th or intercalary month) in the saMvatsara. Now why are there 29 in the outer chakra? That is the rounded off duration of the synodic month i.e
from one parvan to next equivalent parvan. The number 13 arises from the approximate division of the circle by the period of the sidereal month i.e. the time taken by moon to complete a journey from one nakShatra back to the same nakShatra, which is one cycle with the tithi being
the second cycle. The two cycles are thus captured in the chakra-s as befits viShNu quintessential the "deity of time". While these polygons might be inconstructible under the Platonic compass-straight-edge method the H were not bound by those constraints& the divisional angles
are available from astronomical literature corresponding to these cycles. As an aside the use of the equilateral triangle is again not the most popular divisional technique in H architecture except in Kashmir, suvastu&northern Panjab where it is the norm
