John Wallis | |
---|---|

Born | 3 December [ O.S. 23 November] 1616 Ashford, Kent, England |

Died | 8 November 1703 86) [ O.S. 28 October 1703] (aged Oxford, Oxfordshire, England |

Nationality | English |

Education | Felsted School, Emmanuel College, Cambridge |

Known for | Wallis product Inventing the symbol ∞ Extending Cavalieri's quadrature formula Coining the term "momentum" ^{ [1] } |

Scientific career | |

Fields | Mathematics |

Institutions | |

Academic advisors | William Oughtred |

Notable students | William Brouncker |

**John Wallis** ( /ˈwɒlɪs/ ;^{ [2] } Latin : *Wallisius*; 3 December [ O.S. 23 November] 1616 –8 November [ O.S. 28 October] 1703) was an English clergyman and mathematician who is given partial credit for the development of infinitesimal calculus. Between 1643 and 1689 he served as chief cryptographer for Parliament and, later, the royal court.^{ [3] } He is credited with introducing the symbol ∞ to represent the concept of infinity.^{ [4] } He similarly used 1/∞ for an infinitesimal. John Wallis was a contemporary of Newton and one of the greatest intellectuals of the early renaissance of mathematics.^{ [5] }

- Cambridge, M.A., Oxford, D.D.
- Grammar School at Tenterden, Kent, 1625–31.
- School of Martin Holbeach at Felsted, Essex, 1631–2.
- Cambridge University, Emmanuel College, 1632–40; B.A., 1637; M.A., 1640.
- D.D. at Oxford in 1654

On 14 March 1645^{[ which calendar? ]} he married **Susanna Glynde** (c. 1600 – 16 March 1687).^{[ which calendar? ]} They had three children:

- Anne Blencoe (4 June 1656 – 5 April 1718),
^{[ which calendar? ]}married Sir John Blencowe (30 November 1642 – 6 May 1726)^{[ which calendar? ]}in 1675, with issue^{ [6] } **John Wallis**(26 December 1650 – 14 March 1717),^{[ which calendar? ]}^{ [7] }MP for Wallingford 1690–1695, married Elizabeth Harris (d. 1693) on 1 February 1682,^{[ which calendar? ]}with issue: one son and two daughters**Elizabeth Wallis**(1658–1703^{ [8] }), married William Benson (1649–1691) of Towcester, died with no issue

John Wallis was born in Ashford, Kent. He was the third of five children of Reverend John Wallis and Joanna Chapman. He was initially educated at a school in Ashford but moved to James Movat's school in Tenterden in 1625 following an outbreak of plague. Wallis was first exposed to mathematics in 1631, at Felsted School (then known as Martin Holbeach's school in Felsted); he enjoyed maths, but his study was erratic, since "mathematics, at that time with us, were scarce looked on as academical studies, but rather mechanical" (Scriba 1970). At the school in Felsted, Wallis learned how to speak and write Latin. By this time, he also was proficient in French, Greek, and Hebrew.^{ [9] } As it was intended he should be a doctor, he was sent in 1632 to Emmanuel College, Cambridge.^{ [10] } While there, he kept an *act* on the doctrine of the circulation of the blood; that was said to have been the first occasion in Europe on which this theory was publicly maintained in a disputation. His interests, however, centred on mathematics. He received his Bachelor of Arts degree in 1637 and a Master's in 1640, afterwards entering the priesthood. From 1643 to 1649, he served as a nonvoting scribe at the Westminster Assembly. He was elected to a fellowship at Queens' College, Cambridge in 1644, from which he had to resign following his marriage.

Throughout this time, Wallis had been close to the Parliamentarian party, perhaps as a result of his exposure to Holbeach at Felsted School. He rendered them great practical assistance in deciphering Royalist dispatches. The quality of cryptography at that time was mixed; despite the individual successes of mathematicians such as François Viète, the principles underlying cipher design and analysis were very poorly understood. Most ciphers were ad hoc methods relying on a secret algorithm, as opposed to systems based on a variable key. Wallis realised that the latter were far more secure – even describing them as "unbreakable", though he was not confident enough in this assertion to encourage revealing cryptographic algorithms. He was also concerned about the use of ciphers by foreign powers, refusing, for example, Gottfried Leibniz's request of 1697 to teach Hanoverian students about cryptography.^{ [11] }

Returning to London – he had been made chaplain at St Gabriel Fenchurch in 1643 – Wallis joined the group of scientists that was later to evolve into the Royal Society. He was finally able to indulge his mathematical interests, mastering William Oughtred's *Clavis Mathematicae* in a few weeks in 1647. He soon began to write his own treatises, dealing with a wide range of topics, which he continued for the rest of his life. Wallis wrote the first survey about mathematical concepts in England where he discussed the Hindu-Arabic system.^{ [12] }

Wallis joined the moderate Presbyterians in signing the remonstrance against the execution of Charles I, by which he incurred the lasting hostility of the Independents. In spite of their opposition he was appointed in 1649 to the Savilian Chair of Geometry at Oxford University, where he lived until his death on 8 November [ O.S. 28 October] 1703. In 1650, Wallis was ordained as a minister. After, he spent two years with Sir Richard Darley and Lady Vere as a private chaplain. In 1661, he was one of twelve Presbyterian representatives at the Savoy Conference.

Besides his mathematical works he wrote on theology, logic, English grammar and philosophy, and he was involved in devising a system for teaching a deaf boy to speak at Littlecote House.^{ [13] } William Holder had earlier taught a deaf man, Alexander Popham, to speak "plainly and distinctly, and with a good and graceful tone".^{ [14] } Wallis later claimed credit for this, leading Holder to accuse Wallis of "rifling his Neighbours, and adorning himself with their spoyls".^{ [15] }

The Parliamentary visitation of Oxford that began in 1647 removed many senior academics from their positions, including (in November 1648)^{[ which calendar? ]} the Savilian Professors of Geometry and Astronomy. In 1649 Wallis was appointed as Savilian Professor of Geometry. Wallis seems to have been chosen largely on political grounds (as perhaps had been his Royalist predecessor Peter Turner, who despite his appointment to two professorships never published any mathematical works); while Wallis was perhaps the nation's leading cryptographer and was part of an informal group of scientists that would later become the Royal Society, he had no particular reputation as a mathematician. Nonetheless, Wallis' appointment proved richly justified by his subsequent work during the 54 years he served as Savilian Professor.^{ [16] }

Wallis made significant contributions to trigonometry, calculus, geometry, and the analysis of infinite series. In his *Opera Mathematica* I (1695) he introduced the term "continued fraction".

In 1655, Wallis published a treatise on conic sections in which they were defined analytically. This was the earliest book in which these curves are considered and defined as curves of the second degree. It helped to remove some of the perceived difficulty and obscurity of René Descartes' work on analytic geometry. In the *Treatise on the Conic Sections* Wallis popularised the symbol ∞ for infinity. He wrote, "I suppose any plane (following the *Geometry of Indivisibles* of Cavalieri) to be made up of an infinite number of parallel lines, or as I would prefer, of an infinite number of parallelograms of the same altitude; (let the altitude of each one of these be an infinitely small part 1/∞ of the whole altitude, and let the symbol ∞ denote Infinity) and the altitude of all to make up the altitude of the figure."^{ [17] }

*Arithmetica Infinitorum*, the most important of Wallis's works, was published in 1656. In this treatise the methods of analysis of Descartes and Cavalieri were systematised and extended, but some ideas were open to criticism. He began, after a short tract on conic sections, by developing the standard notation for powers, extending them from positive integers to rational numbers:

Leaving the numerous algebraic applications of this discovery, he next proceeded to find, by integration, the area enclosed between the curve *y* = *x*^{m}, *x*-axis, and any ordinate *x* = *h*, and he proved that the ratio of this area to that of the parallelogram on the same base and of the same height is 1/(*m* + 1), extending Cavalieri's quadrature formula. He apparently assumed that the same result would be true also for the curve *y* = *ax*^{m}, where *a* is any constant, and *m* any number positive or negative, but he discussed only the case of the parabola in which *m* = 2 and the hyperbola in which *m* = −1. In the latter case, his interpretation of the result is incorrect. He then showed that similar results may be written down for any curve of the form

and hence that, if the ordinate *y* of a curve can be expanded in powers of *x*, its area can be determined: thus he says that if the equation of the curve is *y* = *x*^{0} + *x*^{1} + *x*^{2} + ..., its area would be *x* + x^{2}/2 + *x*^{3}/3 + ... . He then applied this to the quadrature of the curves *y* = (*x* − *x*^{2})^{0}, *y* = (*x* − *x*^{2})^{1}, *y* = (*x* − *x*^{2})^{2}, etc., taken between the limits *x* = 0 and *x* = 1. He shows that the areas are, respectively, 1, 1/6, 1/30, 1/140, etc. He next considered curves of the form *y* = *x*^{1/m} and established the theorem that the area bounded by this curve and the lines *x* = 0 and *x* = 1 is equal to the area of the rectangle on the same base and of the same altitude as *m* : *m* + 1. This is equivalent to computing

He illustrated this by the parabola, in which case *m* = 2. He stated, but did not prove, the corresponding result for a curve of the form *y* = *x*^{p/q}.

Wallis showed considerable ingenuity in reducing the equations of curves to the forms given above, but, as he was unacquainted with the binomial theorem, he could not effect the quadrature of the circle, whose equation is , since he was unable to expand this in powers of *x*. He laid down, however, the principle of interpolation. Thus, as the ordinate of the circle is the geometrical mean of the ordinates of the curves and , it might be supposed that, as an approximation, the area of the semicircle which is might be taken as the geometrical mean of the values of

that is, and ; this is equivalent to taking or 3.26... as the value of π. But, Wallis argued, we have in fact a series ... and therefore the term interpolated between and ought to be chosen so as to obey the law of this series.^{[ clarification needed ]} This, by an elaborate method that is not described here in detail, leads to a value for the interpolated term which is equivalent to taking

(which is now known as the Wallis product).

In this work also the formation and properties of continued fractions are discussed, the subject having been brought into prominence by Brouncker's use of these fractions.

A few years later, in 1659, Wallis published a tract containing the solution of the problems on the cycloid which had been proposed by Blaise Pascal. In this he incidentally explained how the principles laid down in his *Arithmetica Infinitorum* could be used for the rectification of algebraic curves and gave a solution of the problem to rectify (i.e., find the length of) the semicubical parabola *x*^{3} = *ay*^{2}, which had been discovered in 1657 by his pupil William Neile. Since all attempts to rectify the ellipse and hyperbola had been (necessarily) ineffectual, it had been supposed that no curves could be rectified, as indeed Descartes had definitely asserted to be the case. The logarithmic spiral had been rectified by Evangelista Torricelli and was the first curved line (other than the circle) whose length was determined, but the extension by Neile and Wallis to an algebraic curve was novel. The cycloid was the next curve rectified; this was done by Christopher Wren in 1658.

Early in 1658 a similar discovery, independent of that of Neile, was made by van Heuraët, and this was published by van Schooten in his edition of Descartes's *Geometria* in 1659. Van Heuraët's method is as follows. He supposes the curve to be referred to rectangular axes; if this is so, and if (*x*, *y*) are the coordinates of any point on it, and *n* is the length of the normal,^{[ clarification needed ]} and if another point whose coordinates are (*x*, *η*) is taken such that *η* : *h* = *n* : *y*, where *h* is a constant; then, if *ds* is the element of the length of the required curve, we have by similar triangles *ds* : *dx* = *n* : *y*. Therefore, *h ds* = *η**dx*. Hence, if the area of the locus of the point (*x*, *η*) can be found, the first curve can be rectified. In this way van Heuraët effected the rectification of the curve *y*^{3} = *ax*^{2} but added that the rectification of the parabola *y*^{2} = *ax* is impossible since it requires the quadrature of the hyperbola. The solutions given by Neile and Wallis are somewhat similar to that given by van Heuraët, though no general rule is enunciated, and the analysis is clumsy. A third method was suggested by Fermat in 1660, but it is inelegant and laborious.

The theory of the collision of bodies was propounded by the Royal Society in 1668 for the consideration of mathematicians. Wallis, Christopher Wren, and Christiaan Huygens sent correct and similar solutions, all depending on what is now called the conservation of momentum; but, while Wren and Huygens confined their theory to perfectly elastic bodies (elastic collision), Wallis considered also imperfectly elastic bodies (inelastic collision). This was followed in 1669 by a work on statics (centres of gravity), and in 1670 by one on dynamics: these provide a convenient synopsis of what was then known on the subject.

In 1685 Wallis published *Algebra*, preceded by a historical account of the development of the subject, which contains a great deal of valuable information. The second edition, issued in 1693 and forming the second volume of his *Opera*, was considerably enlarged. This algebra is noteworthy as containing the first systematic use of formulae. A given magnitude is here represented by the numerical ratio which it bears to the unit of the same kind of magnitude: thus, when Wallis wants to compare two lengths he regards each as containing so many units of length. This perhaps will be made clearer by noting that the relation between the space described in any time by a particle moving with a uniform velocity is denoted by Wallis by the formula

*s*=*vt*,

where *s* is the number representing the ratio of the space described to the unit of length; while the previous writers would have denoted the same relation by stating what is equivalent to the proposition

*s*_{1}:*s*_{2}=*v*_{1}*t*_{1}:*v*_{2}*t*_{2}.

Wallis has been credited as the originator of the number line "for negative quantities"^{ [18] } and "for operational purposes."^{ [19] } This is based on a passage in his 1685 treatise on algebra in which he introduced a number line to illustrate the legitimacy of negative quantities:^{ [20] }

Yet is not that Supposition (of Negative Quantities) either Unuseful or Absurd; when rightly understood. And though, as to the bare Algebraick Notation, it import a Quantity less than nothing: Yet, when it comes to a Physical Application, it denotes as Real a Quantity as if the Sign were ; but to be interpreted in a contrary sense... , signifies Yards Forward; and , signifies Yards Backward.

It has also been noted that, in an earlier work, Wallis came to the conclusion that the ratio of a positive number to a negative one is greater than infinity. The argument involves the quotient and considering what happens as approaches and then crosses the point from the positive side.^{ [21] } Wallis was not alone in this thinking: Leonhard Euler came to the same conclusion by considering the geometric series , evaluated at , followed by reasoning similar to Wallis's (he resolved the paradox by distinguishing different kinds of negative numbers).^{ [18] }

He is usually credited with the proof of the Pythagorean theorem using similar triangles. However, Thabit Ibn Qurra (AD 901), an Arab mathematician, had produced a generalisation of the Pythagorean theorem applicable to all triangles six centuries earlier. It is a reasonable conjecture that Wallis was aware of Thabit's work.^{ [22] }

Wallis was also inspired by the works of Islamic mathematician Sadr al-Tusi, the son of Nasir al-Din al-Tusi, particularly by al-Tusi's book written in 1298 on the parallel postulate. The book was based on his father's thoughts and presented one of the earliest arguments for a non-Euclidean hypothesis equivalent to the parallel postulate. After reading this, Wallis then wrote about his ideas as he developed his own thoughts about the postulate, trying to prove it also with similar triangles.^{ [23] }

He found that Euclid's fifth postulate is equivalent to the one currently named "Wallis postulate" after him. This postulate states that "On a given finite straight line it is always possible to construct a triangle similar to a given triangle". This result was encompassed in a trend trying to deduce Euclid's fifth from the other four postulates which today is known to be impossible. Unlike other authors, he realised that the unbounded growth of a triangle was not guaranteed by the four first postulates.^{ [24] }

Another aspect of Wallis's mathematical skills was his ability to do mental calculations. He slept badly and often did mental calculations as he lay awake in his bed. One night he calculated in his head the square root of a number with 53 digits. In the morning he dictated the 27-digit square root of the number, still entirely from memory. It was a feat that was considered remarkable, and Henry Oldenburg, the Secretary of the Royal Society, sent a colleague to investigate how Wallis did it. It was considered important enough to merit discussion in the *Philosophical Transactions* of the Royal Society of 1685.^{ [25] }^{ [26] }

Wallis translated into Latin works of Ptolemy and Bryennius, and Porphyrius's commentary on Ptolemy. He also published three letters to Henry Oldenburg concerning tuning. He approved of equal temperament, which was being used in England's organs.^{ [27] }

His *Institutio logicae*, published in 1687, was very popular.^{ [4] } The *Grammatica linguae Anglicanae* was a work on English grammar, that remained in print well into the eighteenth century. He also published on theology.^{ [4] }

- 31982 Johnwallis, an asteroid that was named after him
- Invisible College
- John Wallis Academy – former ChristChurch school in Ashford renamed in 2010
- Wallis's conical edge
- Wallis' integrals

- ↑ Joseph Frederick Scott,
*The mathematical work of John Wallis (1616-1703)*, Taylor and Francis, 1938, p. 109. - ↑
*Random House Dictionary*. - ↑ Smith, David Eugene (1917). "John Wallis As a Cryptographer".
*Bulletin of the American Mathematical Society*.**24**(2): 82–96. doi: 10.1090/s0002-9904-1917-03015-7 . MR 1560009. - 1 2 3 Chisholm, Hugh, ed. (1911).
*Encyclopædia Britannica*. Vol. 28 (11th ed.). Cambridge University Press. p. 284–285. . - ↑ Kearns, D. A. (1958). "John Wallis and complex numbers".
*The Mathematics Teacher*.**51**(5): 373–374. JSTOR 27955680. - ↑ Joan Thirsk, 'Blencowe , Anne, Lady Blencowe (1656–1718)’, Oxford Dictionary of National Biography, Oxford University Press, Oct 2005; online edn, Jan 2007 accessed 16 Nov 2016
- ↑ WALLIS, John (1650-1717), of Soundness, Nettlebed, Oxon. | History of Parliament Online
- ↑ Early Modern Letters Online : Person
- ↑ Yule, G. Udny (1939). "John Wallis, D.D., F.R.S.".
*Notes and Records of the Royal Society of London*.**2**(1): 74–82. doi:10.1098/rsnr.1939.0012. JSTOR 3087253. - ↑ "Wallys, John (WLS632J)".
*A Cambridge Alumni Database*. University of Cambridge. - ↑ Kahn, David (1967),
*The Codebreakers: The Story of Secret Writing*, New York: Macmillan, p. 169, LCCN 63016109 - ↑ 4
- ↑ "Find could end 350-year science dispute". BBC. 26 July 2008. Retrieved 5 May 2018.
- ↑ W. Holder, W. (1668). "Of an Experiment, Concerning Deafness".
*Philosophical Transactions of the Royal Society*3, pp. 665–668. - ↑ Holder,
*Philosophical Transactions of the Royal Society*, supplement, 10. - ↑ John Wallis: Time-line via Oxford University
- ↑ Scott, J.F. 1981. ‘'The Mathematical Work of John Wallis, D.D., F.R.S. (1616–1703)’’. Chelsea Publishing Co. New York, NY. p. 18.
- 1 2 Heeffer, Albrecht (10 March 2011). "Historical Objections Against the Number Line".
*Science & Education*.**20**(9): 863–880 [872–876]. Bibcode:2011Sc&Ed..20..863H. doi:10.1007/s11191-011-9349-0. hdl:1854/LU-1891046. S2CID 120058064. - ↑ Núñez, Rafael (2017). "How Much Mathematics Is "Hardwired," If Any at All: Biological Evolution, Development, and the Essential Role of Culture" (PDF). In Sera, Maria D.; Carlson, Stephanie M.; Maratsos, Michael (eds.).
*Minnesota Symposium on Child Psychology: Culture and Developmental Systems, Volume 38*. John Wiley & Sons, Inc. pp. 83–124 [96]. doi:10.1002/9781119301981.ch3. - ↑ Wallis, John (1685).
*A treatise of algebra, both historical and practical*. London: Richard Davis. p. 265. MPIWG:GK8U243K. - ↑ Martínez, Alberto A. (2006).
*Negative Math: How Mathematical Rules Can Be Positively Bent*. Princeton University Press. p. 22. ISBN 978-0-691-12309-7 . Retrieved 9 June 2013. - ↑ Joseph, G.G. (2000).
*The Crest of the Peacock: Non-European Roots of Mathematics*(2 ed.). Penguin. p. 337. ISBN 978-0-14-027778-4. - ↑ The Mathematics of Egypt, Mesopotamia, China, India, and Islam:A Sourcebook Victor J. Katz Princeton University Press
- ↑ Burton, David M. (2011),
*The History of Mathematics / An Introduction*(7th ed.), McGraw-Hill, p. 566, ISBN 978-0-07-338315-6 - ↑ Dr. Wallis (1685) "Two extracts of the Journal of the Phil. Soc. of Oxford; one containing a paper, communicated March 31, 1685, by the Reverend Dr. Wallis, president of that society, concerning the strength of memory when applied with due attention; … ",
*Philosophical Transactions of the Royal Society of London*,**15**: 1269-1271. Available on-line at: Royal Society of London^{[ permanent dead link ]} - ↑ Hoppen, K. Theodore (2013),
*The Common Scientist of the Seventeenth Century: A Study of the Dublin Philosophical Society, 1683–1708*, Routledge Library Editions: History & Philosophy of Science, vol. 15, Routledge, p. 157, ISBN 9781135028541 - ↑ David Damschoder and David Russell Williams,
*Music Theory from Zarlino to Schenker: A Bibliography and Guide*(Stytvesant, NY: Pendragon Press, 1990), p. 374.

In mathematics, the **arithmetic–geometric mean** of two positive real numbers *x* and *y* is defined as follows:

In analytic geometry, an **asymptote** of a curve is a line such that the distance between the curve and the line approaches zero as one or both of the *x* or *y* coordinates tends to infinity. In projective geometry and related contexts, an asymptote of a curve is a line which is tangent to the curve at a point at infinity.

In mathematics, a **complex number** is an element of a number system that extends the real numbers with a specific element denoted i, called the imaginary unit and satisfying the equation ; every complex number can be expressed in the form , where a and b are real numbers. Because no real number satisfies the above equation, i was called an imaginary number by René Descartes. For the complex number , a is called the **real part**, and b is called the **imaginary part**. The set of complex numbers is denoted by either of the symbols or **C**. Despite the historical nomenclature "imaginary", complex numbers are regarded in the mathematical sciences as just as "real" as the real numbers and are fundamental in many aspects of the scientific description of the natural world.

A **superellipse**, also known as a **Lamé curve** after Gabriel Lamé, is a closed curve resembling the ellipse, retaining the geometric features of semi-major axis and semi-minor axis, and symmetry about them, but a different overall shape.

The **imaginary unit** or **unit imaginary number** is a solution to the quadratic equation . Although there is no real number with this property, i can be used to extend the real numbers to what are called complex numbers, using addition and multiplication. A simple example of the use of i in a complex number is .

**Abraham de Moivre** FRS was a French mathematician known for de Moivre's formula, a formula that links complex numbers and trigonometry, and for his work on the normal distribution and probability theory.

In mathematics, **Stirling's approximation** is an approximation for factorials. It is a good approximation, leading to accurate results even for small values of . It is named after James Stirling, though a related but less precise result was first stated by Abraham de Moivre.

In geometry, **Heron's formula**, named after Hero of Alexandria, gives the area of a triangle when the lengths of all three sides are known. Unlike other triangle area formulae, there is no need to calculate angles or other distances in the triangle first.

The **square root of 2** is a positive real number that, when multiplied by itself, equals the number 2. It may be written in mathematics as or , and is an algebraic number. Technically, it should be called the principal square root of 2, to distinguish it from the negative number with the same property.

In mathematics, Felix Klein's **j-invariant** or **j function**, regarded as a function of a complex variable τ, is a modular function of weight zero for SL(2, **Z**) defined on the upper half-plane of complex numbers. It is the unique such function which is holomorphic away from a simple pole at the cusp such that

In number theory, a **Heegner number** is a square-free positive integer *d* such that the imaginary quadratic field has class number 1. Equivalently, its ring of integers has unique factorization.

In geometry, **hyperbolic angle** is a real number determined by the area of the corresponding hyperbolic sector of *xy* = 1 in Quadrant I of the Cartesian plane. The hyperbolic angle parametrises the unit hyperbola, which has hyperbolic functions as coordinates. In mathematics, hyperbolic angle is an invariant measure as it is preserved under hyperbolic rotation.

A **fraction** represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, three-quarters. A *common*, *vulgar*, or *simple* fraction consists of a **numerator**, displayed above a line, and a non-zero **denominator**, displayed below that line. Numerators and denominators are also used in fractions that are not *common*, including compound fractions, complex fractions, and mixed numerals.

**Arc length** is the distance between two points along a section of a curve.

In mathematics, the **lemniscate constant**ϖ is a transcendental mathematical constant that is the ratio of the perimeter of Bernoulli's lemniscate to its diameter, analogous to the definition of π for the circle. It is closely related to the lemniscate elliptic functions and approximately equal to 2.62205755. The symbol ϖ is a cursive variant of π; see Pi § Variant pi.

In mathematics, the **plastic number***ρ* is a mathematical constant which is the unique real solution of the cubic equation

In algebra, a **nested radical** is a radical expression that contains (nests) another radical expression. Examples include

In mathematics, a **cuspidal cubic** or **semicubical parabola** is an algebraic plane curve that has an implicit equation of the form

In mathematics, **Viviani's curve**, also known as **Viviani's window**, is a figure eight shaped space curve named after the Italian mathematician Vincenzo Viviani. It is the intersection of a sphere with a cylinder that is tangent to the sphere and passes through two poles of the sphere. Before Viviani this curve was studied by Simon de La Loubère and Gilles de Roberval.

In general, exponentiation fails to be commutative. However, the equation holds in special cases, such as

- The initial text of this article was taken from the public domain resource:
- W. W. Rouse Ball (1908)
*A Short Account of the History of Mathematics,*4th ed. - Scriba, C J (1970). "The autobiography of John Wallis, F.R.S.".
*Notes and Records of the Royal Society of London*.**25**: 17–46. doi:10.1098/rsnr.1970.0003. S2CID 145393357. - Stedall, Jacqueline, 2005, "Arithmetica Infinitorum" in Ivor Grattan-Guinness, ed.,
*Landmark Writings in Western Mathematics*. Elsevier: 23–32. - Guicciardini, Niccolò (2012) "John Wallis as editor of Newton's Mathematical Work",
*Notes and Records of the Royal Society of London*66(1): 3–17. Jstor link - Stedall, Jacqueline A. (2001) "Of Our Own Nation: John Wallis's Account of Mathematical Learning in Medieval England", Historia Mathematica 28: 73.
- Wallis, J. (1691). A seventh letter, concerning the sacred Trinity occasioned by a second letter from W.J. / by John Wallis ... (Early English books online). London: Printed for Tho. Parkhurst ...

- Media related to John Wallis at Wikimedia Commons

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- The Correspondence of John Wallis in EMLO
*Dictionary of National Biography*. London: Smith, Elder & Co. 1885–1900. . - O'Connor, John J.; Robertson, Edmund F., "John Wallis",
*MacTutor History of Mathematics archive*, University of St Andrews - Galileo Project page
- "Archival material relating to John Wallis". UK National Archives.
- Portraits of John Wallis at the National Portrait Gallery, London
- Works by John Wallis at Post-Reformation Digital Library
- John Wallis (1685)
*A treatise of algebra*- digital facsimile, Linda Hall Library - Wallis, John (1685).
*A Treatise of Algebra, both Historical and Practical. Shewing the Original, Progress, and Advancement thereof, from time to time, and by what Steps it hath attained to the Heighth at which it now is*. Oxford: Richard Davis. doi:10.3931/e-rara-8842. - Hutchinson, John (1892).
*Men of Kent and Kentishmen*(Subscription ed.). Canterbury: Cross & Jackman. pp. 139–140. .

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