Self Vision
Self Vision

@selfvision

47 Tweets 18 reads Dec 03, 2023
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This is a thread on two geometry problems: circling the square & squaring the circle. These problems were first proposed & analyzed by ancient Indian Hindus before 2000 BCE. They also designed multiple methods & provided approximate solutions before 800 BCE
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Circling the square is an important problem in geometry which refers to the problem of constructing a circle with the same area as that of a given square.
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The inverse problem is known as squaring the circle, which is the problem of constructing a square with the area of a given circle.
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Both these problems were studied by the ancient Indian mathematicians since at least 2000 BCE, as we will see in this thread
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Before we delve into the actual numerical recipes that ancient Indians invented to solve these problems, we will take a brief detour and try to understand why these problems with specific geometric constraints were important to the followers of Vedic systems in India.
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The problems of circling the square and squaring the circle were rooted in how ancient Indians looked into the process of self-realization - specifically the science & art of Yajna (เคฏเคœเฅเคž) - fire based rituals.
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An important part of the process of performing these Yajnas is described in Shulba Sutras.
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Shulba Sutras are part of Kalpa Sutras in Veclic literature, an enormous body of work dealing with means of self-realization. There are four main Shulba Sutras - Baudhayana, Apastamba, Manava, Katyayana, & a number of smaller ones.
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Shulba Sutras are used to construct physical altars for Yajna. These altars are called โ€˜chiti' in Sanskrit (เคšเคฟเคคเคฟ). Chitis are complex 3D structures - construction of which requires advanced knowledge of geometrical skills.
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A chiti (เคšเคฟเคคเคฟ) is a basis that symbolizes Chitta (เคšเคฟเคคเฅเคค) or consciousness.
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The general format for the main Shulba Sutras are the same - each starts with sections on geometrical and arithmetical constructions and ends with details of how to build โ€œchitisโ€.
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When the Shulba Sutras are viewed as a whole, instead of collection of parts, then a striking level of mathematical efficiency & integrity becomes apparent.
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Literal meaning of the word Shulba is rope. In its true essence Shulba represents both connection & evolution from individual consciousness to the universal consciousness.
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Agni (เค…เค—เฅเคจเคฟ) or fire has huge importance in Vedic knowledge system. Agni is the seer-will in the universe unerring in all its works. He is a truth conscious soul, a seer, a priest and a worker, the immortal worker in all beings.
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All offerings during a Yagna are made to Agni - which is the ultimate transforming agent. There are three specific เคšเคฟเคคเคฟ which are of primary importance in Vedic Knowledge system.
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There are three essential เคšเคฟเคคเคฟ or altars in Vedic rituals: namely เค—เคพเคฐเฅเคนเคชเคคเฅเคฏ (Garhapatya), เค†เคนเคตเคจเฅ€เคฏ (Ahavaniya) and เคฆเค•เฅเคทเคฟเคฃเคพเค—เฅเคจเคฟ (Dakshinagni). The fire kindled in these altars are known as Tretagni & are directly related to the geometry problems mentioned in this thread.
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These three altars (Garhapatya, Ahavaniya and Dakshinagni) need to be constructed in such a way so that the bases of all of them have the same area but each base has a different shape (Garhapatya: circular, Ahavaniya: square and Dakshinagni: semi-circular)
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The geometric problems of circling the square & squaring the circle can be traced back to this constraint
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The earliest reference to that constraint in building these altars is found in Shatapatha Brahmana (เคถเคคเคชเคฅเคฌเฅเคฐเคพเคนเฅเคฎเคฃ) - 7.1.1.37 (no later than 2000 BCE). The original Sanskrit text of the verse & its contextual translation are provided below.
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Now that we know why ancient Indians wanted to solve the problems of circling the square and squaring the circle problems, letโ€™s look into what solutions they came up with.
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The first reference to an approximation solution to circling the square problem is found in the Baudhayana Shulba Sutra
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The translation of Baudhayana Shulba Sutra 1.58 for finding an approximate solution to circling the square problem is given below
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Letโ€™s illustrate Baudhayanaโ€™s method of circling the square step by step. Let ABCD be a square for which we want to find out a circle whose area is approximately the same as the area the square.
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First we join OA
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Then we draw an east west line by drawing a line that goes through the point C and is perpendicular to both AB and CD
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We then divide the line segment WP so that WM is one third of WP
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Finally we draw a circle with O as center and OM as radius. This is our desired circle (drawn in purple here)
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We know that the method specified in the Shulba Sutras for circling a square is meant to find an approximate solution. Letโ€™s find out the how closely the circle estimates the given square
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Apastamba Shulba Sutra also gives a very similar recipe for circling the square as provided in the Baudhayana Shula Sutra
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It is interesting to note that ancient Indian mathematicians were very aware of the approximate nature of this numerical recipe for circling the square
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In Apastamba Shulba Sutra it is specifically mentioned that the method was provided as an approximation and not as an exact solution. Apastamba mentioned โ€œIt is an inexact method construction of the circle; by as much as the circle falls short, so much comes inโ€
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Manava Shulba Sutra gives an even more accurate recipe as a solution to circling the square problem
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The translation of the above verse from the Manava Shulba Sutra is given below
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The geometrical recipe mentioned in Manava Shulba Sutra 11.15 is given below in the diagram.
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The construction method and error analysis of the recipe of circling the square problem in Manava Shulba Sutra is given below
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Now, we will talk about squaring the circling problem. The first reference to approximate solution of the problem is found in Baudhayana Shulba Sutra
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The translation of the recipe for squaring the circling problem as described in Baudhayana Shulba Sutra 1.10 is given below
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An Analysis of the solution prescribed in the Baudhayana Shulba Sutra 1.10 is given below
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Ancient Greeks thought the problem of constructing a square whose area is that of a circle can be solved exactly rather than an approximation to it.
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The first known Greek to study the problem was Anaxagoras (5th century BCE), who worked on it while in prison.
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Antiphon the Sophist (5th century BC) thought that inscribing regular polygons within a circle and doubling the number of sides would eventually fill up the area of the circle
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Ancient Greeks, of course failed in finding an exact solution, as it was theoretically possible.
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In 1882 CE, the Lindemannโ€“Weierstrass theorem proved that squaring the circle problem is impossible to solve if one desires an exact solution.
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In summary, ancient Indians have been studying circling the square & squaring the circle problems since at least 2000 BCE. They designed an approximate solution to both these problems and utilized it to construct magnificent 3D structures.
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The solution to circling the square & squaring the circle problems by ancient Indians laid the foundation of many recipes for an important mathematical field which today is known as computational geometry.
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References
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Correction: In 42/N of it should have said
"Ancient Greeks, of course failed in finding an exact solution, as it was theoretically impossible"

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