Tag Archives: Aryabhatta

Pi-Day and Aryabhatta – Setting the Record Straight

On Pi- Day, ( March 14th represented by 3.14), there is a lot of discussion about how the symbol for Pi, was first used by William Jones and how the value of pi was first used by Archimedes. However, the value of pi to its correct approximation to 4 digits was first proposed by Aryabhatta. On Pi-Day, it is important to remember the contribution of this great Rishi of Bharat.


Aryabhatta is the first in the line of great mathematician-astronomers from the classical age of Indian mathematics and Indian astronomy. His most famous works are the Aryabhatiya and Arya-Siddhanta.

Works:  Aryabhatta is the author of several treatises on mathematics and astronomy, some of which are lost. His major work, Aryabhatiya, a compendium of mathematics and astronomy, was extensively referred to in the Indian mathematical literature, and has survived to modern times.

The Arya-siddhanta, a lost work on astronomical computations, is known through the writings of Aryabhata’s contemporary Varahamihira, as well as through later mathematicians and commentators including Brahmagupta and Bhaskara I. This work appears to be based on the older Surya Siddhanta, and uses the midnight-day-reckoning, as opposed to sunrise in Aryabhatiya. This also contained a description of several astronomical instruments, the gnomon (shanku-yantra), a shadow instrument (chhAyA-yantra), possibly angle-measuring devices, semi-circle and circle shaped (dhanur-yantra / chakra-yantra), a cylindrical stick yasti-yantra, an umbrella-shaped device called chhatra-yantra, and water clocks of at least two types, bow-shaped and cylindrical A third text that may have survived in Arabic translation is the Al ntf or Al-nanf, which claims to be a translation of Aryabhata, but the Sanskrit name of this work is not known. Probably dating from the ninth c., it is mentioned by the Persian scholar and chronicler of India, Abu Rayhan al-Beruni.


Direct details of Aryabhata’s work are therefore known only from the Aryabhatiya. The name Aryabhatiya is due to later commentators, Aryabhata himself may not have given it a name; it is referred by his disciple Bhaskara I as Ashmakatantra or the treatise from the Ashmaka. It is also occasionally referred to as Arya-shatas-aShTa, lit., Aryabhata’s 108, which is the number of verses in the text. It is written in the very terse style typical of the sutra literature, where each line is an aid to memory for a complex system. Thus, the explication of meaning is due to commentators. The entire text consists of 108 verses, plus an introductory 13, the whole being divided into four pAdas or chapters:

gitikApAda: (13 verses) large units of time – kalpa, manvantra, yuga, which present cosmology that differs from texts such as Lagadha’s Vedanga Jyotisha. Also includes the table of sines (jya), given in a single verse. For the planetary revolutions during a mahayuga, the number of 4.32mn years is given.

gaNitapAda (33 verses), covering mensuration (kShetra vyAvahAra), arithmetic and geometric progressions, gnomon / shadows (shanku-chhAyA), simple, quadratic, simultaneous, and indeterminate equations (kuTTaka)

kAlakriyApAda (25 verses) : different units of time and method of determination of positions of planets for a given day. Calculations concerning the intercalary month (adhikamAsa), kShaya-tithis. Presents a seven-day week, with names for days of week.

golapAda (50 verses): Geometric/trigonometric aspects of the celestial sphere, features of the ecliptic, celestial equator, node, shape of the earth, cause of day and night, rising of zodiacal signs on horizon etc.

In addition, some versions cite a few colophons added at the end, extolling the virtues of the work, etc.

The Aryabhatiya presented a number of innovations in mathematics and astronomy in verse form, which were influential for many centuries. The extreme brevity of the text was elaborated in commentaries by his disciple Bhaskara I and by Nilakantha Somayaji in his Aryabhatiya Bhasya.


Place Value system and zero

The number place-value system, first seen in the 3rd century Bakhshali Manuscript was clearly in place in his work; he certainly did not use the symbol, but the French mathematician Georges Ifrah argues that knowledge of zero was implicit in Aryabhata’s place-value system as a place holder for the powers of ten with null coefficients.

However, Aryabhata did not use the brahmi numerals; continuing the Sanskritic tradition from Vedic times, he used letters of the alphabet to denote numbers, expressing quantities (such as the table of sines) in a mnemonic form.

Pi as Irrational Aryabhata worked on the approximation for Pi, and may have realized that Pi is irrational. In the second part of the Aryabhatiyam , he writes

chaturadhikam satamasaguam dvasasistatatha sahasraam Ayutadvayavi kambhasyasanno vrîttapariaha.

“Add four to 100, multiply by eight and then add 62,000. By this rule the circumference of a circle of diameter 20,000 can be approached.”

In other words, Pi = ~ 62832/20000 = 3.1416, correct to five digits. The commentator Nilakantha Somayaji, (Kerala School, 15th c.) interprets the word ?sanna (approaching), appearing just before the last word, as saying that not only that is this an approximation, but that the value is incommensurable (or irrational). If this is correct, it is quite a sophisticated insight, for the irrationality of pi was proved in Europe only in 1761 by Lambert).

After Aryabhatiya was translated into Arabic (ca. 820 AD) this approximation was mentioned in Al-Khwarizmi’s book on algebra.

Mensuration and trigonometry In Ganitapada 6, Aryabhata gives the area of triangle as ” tribhujasya phalashariram samadalakoti bhujardhasamvargah”

that translates to: for a triangle, the result of a perpendicular with the half-side is the area.

Indeterminate Equations A problem of great interest to Indian mathematicians since ancient times has been to find integer solutions to equations that have the form ax + b = cy, a topic that has come to be known as diophantine equations. Here is an example from Bhaskara’s commentary on Aryabhatiya

Find the number which gives 5 as the remainder when divided by 8; 4 as the remainder when divided by 9; and 1 as the remainder when divided by 7.

i.e. find N = 8x+5 = 9y+4 = 7z+1. It turns out that the smallest value for N is 85. In general, diophantine equations can be notoriously difficult. Such equations were considered extensively in the ancient Vedic text Sulba Sutras, the more ancient parts of which may date back to 800 BCE. Aryabhata’s method of solving such problems, called the kuttaka method. Kuttaka means pulverizing, that is breaking into small pieces, and the method involved a recursive algorithm for writing the original factors in terms of smaller numbers. Today this algorithm, as elaborated by Bhaskara in AD 621, is the standard method for solving first order Diophantine equations, and it is often referred to as the Aryabhata algorithm.

The diophantine equations are of interest in cryptology, and the RSA Conference, 2006, focused on the kuttaka method and earlier work in the Sulvasutras.

Astronomy Aryabhata’s system of astronomy was called the audAyaka system (days are reckoned from uday, dawn at lanka, equator). Some of his later writings on astronomy, which apparently proposed a second model (ardha-rAtrikA, midnight), are lost, but can be partly reconstructed from the discussion in Brahmagupta’s khanDakhAdyaka. In some texts he seems to ascribe the apparent motions of the heavens to the earth’s rotation.

Motions of the Solar System Aryabhata appears to have believed that the earth rotates about its axis. This is made clear in the statement, referring to Lanka , which describes the movement of the stars as a relative motion caused by the rotation of the earth:

Like a man in a boat moving forward sees the stationary objects as moving backward, just so are the stationary stars seen by the people in lankA (i.e. on the equator) as moving exactly towards the West. [achalAni bhAni samapashchimagAni – golapAda.]

But the next verse describes the motion of the stars and planets as real movements: “The cause of their rising and setting is due to the fact the circle of the asterisms together with the planets driven by the provector wind, constantly moves westwards at Lanka”.

Lanka (Sri Lanka) is here a reference point on the equator, which was taken as the equivalent to the reference meridian for astronomical calculations.

Aryabhata described a geocentric model of the solar system, in which the Sun and Moon are each carried by epicycles which in turn revolve around the Earth. In this model the motions of the planets are each governed by two epicycles, a smaller manda (slow) epicycle and a larger ghra (fast) epicycle. The order of the planets in terms of distance from earth are taken as: the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, and the asterisms.

The positions and periods of the planets were calculated relative to uniformly moving points, which in the case of Mercury and Venus, move around the Earth at the same speed as the mean Sun and in the case of Mars, Jupiter, and Saturn move around the Earth at specific speeds representing each planet’s motion through the zodiac. Most historians of astronomy consider that this two epicycle model reflects elements of pre-Ptolemaic Greek astronomy. Another element in Aryabhata’s model, the ghrocca, the basic planetary period in relation to the Sun, is seen by some historians as a sign of an underlying heliocentric model.


He states that the Moon and planets shine by reflected sunlight. Instead of the prevailing cosmogyny where eclipses were caused by pseudo-planetary nodes Rahu and Ketu, he explains eclipses in terms of shadows cast by and falling on earth. Thus the lunar eclipse occurs when the moon enters into the earth-shadow (verse gola.37), and discusses at length the size and extent of this earth-shadow (verses gola.38-48), and then the computation, and the size of the eclipsed part during eclipses. Subsequent Indian astronomers improved on these calculations, but his methods provided the core. This computational paradigm was so accurate that the 18th century scientist Guillaume le Gentil, during a visit to Pondicherry, found the Indian computations of the duration of the lunar eclipse of 1765-08-30 to be short by 41 seconds, whereas his charts (by Tobias Mayer, 1752) were long by 68 seconds.

Aryabhata’s computation of Earth’s circumference as 24,835 miles, which was only 0.2% smaller than the actual value of 24,902 miles. This approximation might have improved on the computation by the Greek mathematician Eratosthenes (c.200 BC), whose exact computation is not known in modern units.

Sidereal periods

Considered  in modern English units of time, Aryabhata calculated the sidereal rotation (the rotation of the earth referenced the fixed stars) as 23 hours 56 minutes and 4.1 seconds; the modern value is 23:56:4.091. Similarly, his value for the length of the sidereal year at 365 days 6 hours 12 minutes 30 seconds is an error of 3 minutes 20 seconds over the length of a year. The notion of sidereal time was known in most other astronomical systems of the time, but this computation was likely the most accurate in the period.


Aryabhata claims that the Earth turns on its own axis and some elements of his planetary epicyclic models rotate at the same speed as the motion of the planet around the Sun. This has suggested to some interpreters that Aryabhata’s calculations were based on an underlying heliocentric model in which the planets orbit the Sun.[12][13] A detailed rebuttal to this heliocentric interpretation is in a review which describes B. L. van der Waerden’s book as “showing a complete misunderstanding of Indian planetary theory [that] is flatly contradicted by every word of Aryabhata’s description,” although some concede that Aryabhata’s system stems from an earlier heliocentric model of which he was unaware. It has even been claimed that he considered the planet’s paths to be elliptical, although no primary evidence for this has been cited. Though Aristarchus of Samos (3rd century BC) and sometimes Heraclides of Pontus (4th century BC) are usually credited with knowing the heliocentric theory, the version of Greek astronomy known in ancient India, Paulisa Siddhanta (possibly by a Paul of Alexandria) makes no reference to a Heliocentric theory.


Aryabhata’s work was of great influence in the Indian astronomical tradition, and influenced several neighbouring cultures through translations. The Arabic translation , was particularly influential. Some of his results are cited by Al-Khwarizmi, and he is referred to by the 10th century Arabic scholar Al-Biruni, who states that Aryabhatta’s followers believed the Earth to rotate on its axis.

His definitions of sine, as well as cosine (kojya), versine (ukramajya), and inverse sine (otkram jya), influenced the birth of trigonometry. He was also the first to specify sine and versine (1 – cosx) tables, in 3.75° intervals from 0° to 90°, to an accuracy of 4 decimal places.

In fact, the modern names “sine” and “cosine”, are a mis-transcription of the words jya and kojya as introduced by Aryabhata. They were transcribed as jiba and kojiba in Arabic. They were then misinterpreted by Gerard of Cremona while translating an Arabic geometry text to Latin; he took jiba to be the Arabic word jaib, which means “fold in a garment”, L. sinus (c.1150).

Aryabhata’s astronomical calculation methods were also very influential. Along with the trigonometric tables, they came to be widely used in the Islamic world, and were used to compute many Arabic astronomical tables (zijes). In particular, the astronomical tables in the work of the Arabic Spain scientist Al-Zarqali (11th c.), were translated into Latin as the Tables of Toledo (12th c.), and remained the most accurate Ephemeris used in Europe for centuries.

Calendric calculations worked out by Aryabhata and followers have been in continuous use in India for the practical purposes of fixing the Panchanga, or Hindu calendar, These were also transmitted to the Islamic world, and formed the basis for the Jalali calendar introduced 1073 by a group of astronomers including Omar Khayyam, versions of which (modified in 1925) are the national calendars in use in Iran and Afghanistan today. The Jalali calendar determines its dates based on actual solar transit, as in Aryabhata (and earlier Siddhanta calendars). This type of calendar requires an Ephemeris for calculating dates. Although dates were difficult to compute, seasonal errors were lower in the Jalali calendar than in the Gregorian calendar..

Source : CBSE Sample Papers


Great Inventions By Indians by OMG

Top 10 Biggest Inventions by Indian People

India has been a prominent center of learning since ancient times. The land was one of the most advanced regions in various fields of science.The Indian subcontinent has been a major contributor to the world and has excelled in fields of astronomy, numerology, arithmetic, mineralogy, metallurgy, logic, information and technology. Some of the inventions even date back to as early as the Indus Valley Civilization. Historical evidences and excavations by archaeologists ascertain the dominance of India in the field of science and technology.

10. Cotton Gin

cotton gin Top 10 Biggest Inventions by Indian People

Cotton Gin is a machine used to separate cotton from the seeds. The evidence of this machine was found through the carvings on Ajanta caves where the pictures of these machines were engraved. Dating back to 500 AD, this hand roller machine was locally called Charkha. This machine has undergone changes through the course of time but the most primitive form of cotton gin originated from India.

9. Buttons

buttons Top 10 Biggest Inventions by Indian People

Buttons are a major part of our clothing even today. Buttons were invented in India and various historical evidences and excavations prove that buttons were used by the people belonging to the Indus Valley Civilization. Shells were given various shapes and were pierced into a hole. Earlier they were used more as an embellishment but were gradually used to fasten clothes.

8.  Natural Fibers

natural fibre Top 10 Biggest Inventions by Indian People

Natural fibers like wool, cotton and plant originated from India. Evidences show that people of the Indus Valley used cotton and India pioneered the art of cotton spinning and used it in making fabric. Jute, a plant fiber, was cultivated in India since ancient times and was later exported to other countries. Cashmere wool, which is supposed to be the finest wool was first made in Kashmir and was used to make hand- made shawls. These shawls have maintained their richness and exclusivity even today.

7. Surgery

cataract surgery Top 10 Biggest Inventions by Indian People

Cataract surgery and plastic surgery were also first performed by the ancient physician Sushruta. These surgeries dated back to 2000BCE and his work were later translated to Arabic language and gradually passed on to European countries. He used a curved needle and removed the cataract by pushing the lens. The eyes were then immersed in warm butter and were properly covered till they were completely healed. People from far off countries came to India to seek treatment.

6. Medical Treatments

ayurveda and siddha medical treatments Top 10 Biggest Inventions by Indian People

Leprosy was first noticed by Indians and various ancient remedies are also mentioned in the Atharva Veda. Lithiasis treatment or the treatment for eradicating stones was first introduced in India. Small Pox vaccinations were first cured in India and symptoms and ways of immunization against small pox were mentioned in 8th century by Madhav. Ayurveda and Siddha are the two primitive methods of treatment that originated in India and are still used as an alternate way of treatment. They were used for holistic healing and ancient sages of India mastered this treatment method. Another Indian medical practitioner named Upendra Nath Bramhachari invented methods to treat Visceral Leishmaniasis or Kala Azar. This Nobel Laureate was responsible for the eradication of this ailment.

5. Diamonds

Diamonds Top 10 Biggest Inventions by Indian People

Diamonds were first mined in India. Huge deposits of diamonds were found in Central India and it gradually developed as a precious stone. India till 18th century was the only country where diamonds were found and were later on exported to other countries. Indians were well aware of the physical properties of diamond like its durability, ability to cut other hard surfaces, sparkling effect and the refractive property. Various ancient books have mentioned the use of diamond as a tool and have also mentioned the exquisiteness of this sparkling stone.

4. Dock

lothal dock Top 10 Biggest Inventions by Indian People

India was the first nation to have a dock that dated back to 2400BCE. People belonging to the Harappa Civilization were the first to build a dock in Lothal. This proves their immense understanding of oceanology and marine engineering. The Lothal Dock proves their precision and vast knowledge about tidal waves and hydrography. Without having a thorough knowledge of these topics, it is impossible to build a dock.

3. Crucible Steel

crucible steel Top 10 Biggest Inventions by Indian People

High-quality steel has been produced in South India since ancient times. The technique used to manufacture it was later on called the crucible technique. Pure wrought iron was first put together with glass and charcoal in a container and was heated till the metal melted and absorbed the carbon.

2. Ink

ink Top 10 Biggest Inventions by Indian People

Ink made from various materials was first invented in India. This black pigment was used in writing manuscripts in ancient India. India ink was made by burning tar, pitch, bones. Carbon was the primary pigment of India ink.

1. Zero

Zero1 Top 10 Biggest Inventions by Indian People

Mathematics does not make sense without zero. Although it has no value, it plays a vital role in Arithmetic. Aryabhatta was a great mathematician and an ace astronomer. His contribution to mathematics is unimaginable. Use of Place Value System was clearly mentioned in Aryabhatta’s Bhakshali manuscript and thus zero came into existence. No particular symbol was given to zero but the presence of zero was evident from his work.