At a glance:

Certain formulae called Ayadi Shadvarga are recommended by the ancient classical works of India when building a residence or temple. These formulae are said to ensure health, wealth and prosperity to the people. These formulae are known as aya, vyaya, rksa, yoni, vara and thithi. Certain texts also mention vayas.

The ancients considered the dwelling as a living organism. Whether it was a temple (prasada) or a palace (rajagruha) or a residential dwelling (sala) or the image (chltra) or idol of a deity (vigraha), perfection was the word that they desired and looked for.

The site (kshetra) and the dwelling (vastu or avastha) were considered as having a rhythm and beauty which vibed perfectly with Nature.

Each site and building had life and there was the necessity of building the structure to perfect proportions based on certain formulae. When houses were built using these formulae, they were said to give the residents health, wealth and prosperity.

Evamaayadhishadvarge kuryathatra vichakshanowhu II

In this (matter of selecting the correct measure) the expert (architect) should apply the set of six formulae beginning with Aya (—Manasara, IX, 74)

So what are these formulae? The group of six formulae to which a structure should conform is known as Ayadi Shadvarga. These formulae are respectively Aya, Vyaya, Rksa, Yoni, Vara and Tithi.

Ayadi Shadvarga test whether the orientation of a building is correct and whether the measurements conform to the orientation. A variety of dimensions are prescribed by the ancient treatises. These shadvarga enable the builder to select auspicious and proper dimensions of the building.

Now let us see how these formulae are calculated with specific reference to the text Manasara.

Odd remainders are said to be auspicious and even remainders, bad. If there is no remainder the breadth has to be altered.

The yoni which is said to be an architectural formula has been given much importance by our ancients. The remainder gained through it guarantees the suitablity of the building and the well being of the master and his surroundings. A proper yoni will ensure the qualitative life of a structure.

Brihat Samhita calculates the yoni in a slightly different manner. The area (length x breadth) is divided by 8.
The auspicious yoni defines the correct orientation of the building.

From the Yoni table above it is clear that the ancients wanted the buildings to face the four cardinal directions only viz., East, West, North and South.

The classical texts opine that Dhwaja Yoni is the best of all auspicious Yonis.

Manusyalaya Chandrika states that
Yoni constitutes the life and breath of a structure particularly of a house.

Yonihi Praanaa Eva Dhamnam Yadasmaad I
Grahyastatadyogyayoniprabhedaha II

Of all the Shadvarga, Aya, Vyaya, Yoni and Nakshatra are extremely important. If the measurement of the building conforms to these four formulae, we can assume that the structure more or less is proportionate.

Manasara recommends 9 different lengths, 9 different breadths and 5 different heights. Of these different and varying measures, the right measure is selected by applying the 6 formulae. By a verification of the measurements with the respective formula, the risk of selecting improper measurements will be eliminated. The ancient structures which conformed to these Ayadi are even today standing strong and tall.

The following slokas from Manasara are appropriate.

Yatra dosho gunadhikyam tatra dosho na vidhyathe I
Tesham adhikagunaam vaanamyaam
sarvadoshakaram bhavet I
Tasmatpariharedh vidhvanjanamevamprakalpayet II

Where there is more excellence than flaw, there is no defect in it, but if the flaw is more than the excellence, it would be imperfect; therefore, the knowledgeable (architect) should avoid the calculation that is imperfect and follow the practice that is current among the people.