pi_1

Introductions to PiIntroduction to the classical constants

General

Golden ratio

The division of a line segment whose total length is a + b into two parts a and b where the ratio of a + b to a is

equal to the ratio a to b is known as the golden ratio. The two ratios are both approximately equal to 1.618..., which

is called the golden ratio constant and usually notated by :

a + b

a

a

b 1.618

1 + 5

2 .

The concept of golden ratio division appeared more than 2400 years ago as evidenced in art and architecture. It is

possible that the magical golden ratio divisions of parts are rather closely associated with the notion of beauty in

pleasing, harmonious proportions expressed in different areas of knowledge by biologists, artists, musicians,

historians, architects, psychologists, scientists, and even mystics. For example, the Greek sculptor Phidias (490430

BC) made the Parthenon statues in a way that seems to embody the golden ratio; Plato (427347 BC), in his

Timaeus, describes the five possible regular solids, known as the Platonic solids (the tetrahedron, cube, octahedron,

dodecahedron, and icosahedron), some of which are related to the golden ratio.

The properties of the golden ratio were mentioned in the works of the ancient Greeks Pythagoras (c. 580c. 500

BC) and Euclid (c. 325c. 265 BC), the Italian mathematician Leonardo of Pisa (1170s or 1180s1250), and the

Renaissance astronomer J. Kepler (15711630). Specifically, in book VI of the Elements, Euclid gave the following

definition of the golden ratio: "A straight line is said to have been cut in extreme and mean ratio when, as the whole

line is to the greater segment, so is the greater to the less". Therein Euclid showed that the "mean and extreme

ratio", the name used for the golden ratio until about the 18th century, is an irrational number.

In 1509 L. Pacioli published the book De Divina Proportione, which gave new impetus to the theory of the golden

ratio; in particular, he illustrated the golden ratio as applied to human faces by artists, architects, scientists, and

mystics. G. Cardano (1545) mentioned the golden ratio in his famous book Ars Magna, where he solved quadratic

and cubic equations and was the first to explicitly make calculations with complex numbers. Later M. Mstlin

(1597) evaluated 1 approximately as 0.6180340 . J. Kepler (1608) showed that the ratios of Fibonacci num-bers approximate the value of the golden ratio and described the golden ratio as a "precious jewel". R. Simson

(1753) gave a simple limit representation of the golden ratio based on its very simple continued fraction

1 + 11+

1

1+

. M. Ohm (1835) gave the first known use of the term "golden section", believed to have originated

earlier in the century from an unknown source. J. Sulley (1875) first used the term "golden ratio" in English and G.

Chrystal (1898) first used this term in a mathematical context.

The symbol (phi) for the notation of the golden ratio was suggested by American mathematician M. Barrwas in

1909. Phi is the first Greek letter in the name of the Greek sculptor Phidias.

Throughout history many people have tried to attribute some kind of magic or cult meaning as a valid description

of nature and attempted to prove that the golden ratio was incorporated into different architecture and art objects

(like the Great Pyramid, the Parthenon, old buildings, sculptures and pictures). But modern investigations (for

example, G. Markowsky (1992), C. Falbo (2005), and A. Olariu (2007)) showed that these are mostly misconcep-

tions: the differences between the golden ratio and real ratios of these objects in many cases reach 2030% or more.

The golden ratio has many remarkable properties related to its quasi symmetry. It satisfies the quadratic equation

z2 - z - 1 0, which has solutions z1 and z2 1 - . The absolute value of the second solution is called thegolden ratio conjugate, F - 1. These ratios satisfy the following relations:

- 1 1

F + 1 1

F.

Applications of the golden ratio also include algebraic coding theory, linear sequential circuits, quasicrystals,

phyllotaxis, biomathematics, and computer science.

Pi

The constant 3.14159 is the most frequently encountered classical constant in mathematics and the natural

sciences. Initially it was defined as the ratio of the length of a circle's circumference to its diameter. Many further

interpretations and applications in practically all fields of qualitative science followed. For instance, the following

table illustrates how the constant is applied to evaluate surface areas and volumes of some simple geometrical

objects:

http://functions.wolfram.com 2

R3Hsurface areaL R3

HvolumeL Rn

Hhyper surface areaL Rn

HhypervolumeLsphereIof radius r and diameter d M S 4 r

2 d2 V 4 3

r3 6

d3 S2 k 2 kHk-1L! r2 k-1

S2 k+1 k 22 k+1 k!H2 kL! r2 k

Sn 2 n2GJ n

2N rn-1

V2 k k

k! r2

V2 k+1 kH2

Vn n2

GJ n+22

N rn

ellipsoid HspheroidLIof semi-axes a , b , c ,or r jM

containingelliptic integrals

V 4 3

a b c containingelliptic integrals

V2 k k

k!

V2 k+1 kH2

Vn n2

GJ n+22

N r jcylinderIof height h and radius r M S 2 r Hr + hL V r

2 h S2 k 22 k k-1 k!H2 kL! r2 k-2 HH2 k - 1L h + 2 rL

S2 k+1 2 k

k! r2 k-1 Hh k + rL

Sn

n-1

2

GJ n+12

N rn-2HHn - 1L h + 2 rL

V2 k 22 k H2

V2 k+1 k

k!

Vn

n-1

2

GJ n+12

N h

coneIof height h and radius r M S r r + r2 + h2 V

3r2 h S2 k

4k k-1 k!H2 kL! r + h2 + r2 r2 k-2

S2 k+1 k r+ h2+r2

k!r2 k-1

Sn

n-1

2 rn-2 r+ h2+r2

GJ n+12

N

V2 k 22 k-1

V2 k+1 H2Vn

n-1

2 h

n GJ n

RHcircumferenceL R2

Hsurface areaLcircleIof radius r and diameter d M c 2 r d S r

2 4

d2

ellipseIof semi-axes a , b M containingelliptic integrals S a b

Different approximations of have been known since antiquity or before when people discovered some basic

properties of circles. The design of Egyptian pyramids (c. 3000 BC) incorporated as

22 7 3 + 1 7 H ~ 3.142857 L in numerous places. The Egyptian scribe Ahmes (Middle Kingdom papyrus, c.2000 BC) wrote the oldest known text to give an approximate value for as H16 9L2 ~ 3.16045. Babylonianmathematicians (19th century BC) were using an estimation of as 25 8, which is within 0.53% of the exactvalue. (China, c. 1200 BC) and the Biblical verse I Kings 7:23 (c. 971852 BC) gave the estimation of as 3.

Archimedes (Greece, c. 240 BC) knew that 3 + 10 71 < < 3 + 1 7 and gave the estimation of as 3.1418.Aryabhata (India, 5th century) gave the approximation of as 62832/20000, correct to four decimal places. Zu

Chongzhi (China, 5th century) gave two approximations of as 355/113 and 22/7 and restricted between

3.1415926 and 3.1415927.


A reinvestigation of began by building corresponding series and other calculus-related formulas for this constant.

Simultaneously, scientists continued to evaluate with greater and greater accuracy and proved different structural

properties of . Madhava of Sangamagrama (India, 13501425) found the infinite series expansion4

1 - 13

+ 15

- 17

+ 19

- (currently named the Gregory-Leibniz series or Leibniz formula) and evaluated with

11 correct digits. Ghyath ad-din Jamshid Kashani (Persia, 1424) evaluated with 16 correct digits. F. Viete (1593)

represented 2 as the infinite product 2

22

2+ 22

2+ 2+ 2

2 . Ludolph van Ceulen (Germany, 1610)

evaluated 35 decimal places of . J. Wallis (1655) represented as the infinite product 2

21

23

43

45

65

67

87

89

. J.

Machin (England, 1706) developed a quickly converging series for , based on the formula

4 4 tan-1I 15

M - tan-1I 1239

M, and used it to evaluate 100 correct digits. W. Jones (1706) introduced the symbol for notation of the Pi constant. L. Euler (1737) adopted the symbol and made it standard. C. Goldbach (1742) also

widely used the symbol . J. H. Lambert (1761) established that is an irrational number. J. Vega (Slovenia, 1789)

improved J. Machin's 1706 formula and calculated 126 correct digits for . W. Rutherford (1841) calculated 152

correct digits for . After 20 years of hard work, W. Shanks (1873) presented 707 digits for , but only 527 digits

were correct (as D. F. Ferguson found in 1947). F. Lindemann (1882) proved that is transcendental. F. C. W.

Stormer (1896) derived the formula 4

44 tan-1I 157

M + 7 tan-1I 1239

M - 12 tan-1I 1682

M + 24 tan-1I 112 943

M, which wasused in 2002 for the evaluation of 1,241,100,000,000 digits of . D. F. Ferguson (1947) recalculated to 808

decimal places, using a mechanical desk calculator. K. Mahler (1953) proved that is not a Liouville number.

Modern computer calculation of was started by D. Shanks (1961), who reported 100000 digits of . This record

was improved many times; Yasumasa Kanada (Japan, December 2002) using a 64-node Hitachi supercomputer

evaluated 1,241,100,000,000 digits of . For this purpose he used the earlier mentioned formula of F. C. W.

Stormer (1896) and the formula 4

12 tan-1I 149

M + 32 tan-1I 157

M - 5 tan-1I 1239

M + 12 tan-1I 1110 443

M. Future improvedresults are inevitable.

Degree

Babylonians divided the circle into 360 degrees (360), probably because 360 approximates the number of days in

a year. Ptolemy (Egypt, c. 90168 AD) in Mathematical Syntaxis used the symbol sing in astronomical calcula-

tions. Mathematically, one degree H1 L has the numerical value 180

:

180.

Therefore, all historical and other information about can be derived from information about .

Euler constant


J. Napier in his work on logarithms (1618) mentioned the existence of a special convenient constant for the calcula-

tion of logarithms (but he did not evaluate this constant). It is possible that the table of logarithms was written by

W. Oughtred, who is credited in 1622 with inventing the slide rule, which is a tool used for multiplication, division,

evaluation of roots, logarithms, and other functions. In 1669 I. Newton published the series

2 + 1 2! + 1 3! + 2.71828 , which actually converges to that special constant. At that time J. Bernoullitried to find the limit of H1 + 1 nLn, when n . G. W. Leibniz (16901691) was the first, in correspondence to C.Huygens, to recognize this limit as a special constant, but he used the notation b to represent it.

L. Euler began using the letter e for that constant in 17271728, and introduced this notation in a letter to C.

Goldbach (1731). However, the first use of e in a published work appeared in Euler's Mechanica (1736). In 1737 L.

Euler proved that and 2 are irrational numbers and represented through continued fractions. In 1748 L. Euler

represented as an infinite sum and found its first 23 digits:

k=0

1

k ! 1 +

1

1+

1

2!+

1

3!+

1

4!+ .

D. Bernoulli (1760) used e as the base of the natural logarithms. J. Lambert (1768) proved that pq is an irrationalnumber, if p q is a nonzero rational number. In the 19th century A. Cauchy (1823) determined that lim

zH1 + 1 zLz; J. Liouville (1844) proved that does

not satisfy any quadratic equation with integral coefficients; C. Hermite (1873) proved that is a transcendental

number; and E. Catalan (1873) represented through infinite products.

The only constant appearing more frequently than in mathematics is . Physical applications of are very often

connected with time-dependent processes. For example, if w HtL is a decreasing value of a quantity at time t, whichdecreases at a rate proportional to its value with coefficient -, this quantity is subject to exponential decay

described by the following differential equation and its solution:

wHtL - t ; wHtL c - twhere c wH0L is the initial quantity at time t 0. Examples of such processes can be found in the following: aradionuclide that undergoes radioactive decay, chemical reactions (like enzyme-catalyzed reactions), electric

charge, vibrations, pharmacology and toxicology, and the intensity of electromagnetic radiation.

Euler gamma

In 1735 the Swiss mathematician L. Euler introduced a special constant that represents the limiting difference

between the harmonic series and the natural logarithm:

limn

k=1

n 1

k- logHnL .


Euler denoted it using the symbol C, and initially calculated its value to 6 decimal places, which he extended to 16

digits in 1781. L. Mascheroni (1790) first used the symbol for the notation of this constant and calculated its

value to 19 correct digits. Later J. Soldner (1809) calculated to 40 correct digits, which C. Gauss and F. Nicolai

(1812) verified. E. Catalan (1875) found the integral representation for this constant 1 - 0

1t2+t4+t8+

t+1 t.

This constant was named the Euler gamma or Euler-Mascheroni constant in the honor of its founders.

Applications include discrete mathematics and number theory.

Catalan constant

The Catalan constant C 1 - 1 32 + 1 52 - 1 72 + 0.915966 ... was named in honor of Eu. Ch. Catalan(18141894), who introduced a faster convergent equivalent series and expressions in terms of integrals. Based on

methods resulting from collaborations with M. Leclert, E. Catalan (1865) computed C up to 9 decimals. M. Bresse

(1867) computed 24 decimals of C using a technique from E. Kummer's work. J. Glaisher (1877) evaluated 20

digits of the Catalan constant, which he extended to 32 digits in 1913.

The Catalan constant is applied in number theory, combinatorics, and different areas of mathematical analysis.

Glaisher constant

The works of H. Kinkelin (1860) and J. Glaisher (18771878) introduced one special constant:

A exp1

12- H-1L ,

which was later called the Glaisher or Glaisher-Kinkelin constant in honor of its founders. This constant is used in

number theory, Bose-Einstein and Fermi-Dirac statistics, analytic approximation and evaluation of integrals and

products, regularization techniques in quantum field theory, and the Scharnhorst effect of quantum electrodynamics.

Khinchin constant

The 1934 work of A. Khinchin considered the limit of the geometric mean of continued fraction terms

limn

Ik=1n qkM1n and found that its value is a constant independent for almost all continued fractions:q0 +

1

q1 +1

q2+1

q3+

x qk N+.

The constantnamed the Khinchin constant in the honor of its founderestablished that rational numbers, solu-

tions of quadratic equations with rational coefficients, the golden ratio , and the Euler number upon being

expanded into continued fractions do not have the previous property. Other site numerical verifications showed that

continued fraction expansions of , the Euler-Mascheroni constant , and Khinchin's constant K itself can satisfy

that property. But it was still not proved accurately.

Applications of the Khinchin constant K include number theory.

Imaginary unit


The imaginary unit constant allows the real number system R to be extended to the complex number system C.

This system allows for solutions of polynomial equations such as z2 + 1 0 and more complicated polynomial

equations through complex numbers. Hence 2 -1 and H-L2 -1, and the previous quadratic equation has twosolutions as is expected for a quadratic polynomial:

z2 -1 ; z z1 z z2 -.The imaginary unit has a long history, which started with the question of how to understand and interpret the

solution of the simple quadratic equation z2 -1.

It was clear that 12 H-1L2 1. But it was not clear how to get -1 from something squared. In the 16th, 17th, and 18th centuries this problem was intensively discussed together with the problem of solving

the cubic, quartic, and other polynomial equations. S. Ferro (Italy, 14651526) first discovered a method to solve

cubic equations. N. F. Tartaglia (Italy, 15001557) independently solved cubic equations. G. Cardano (Italy, 1545)

published the solutions to the cubic and quartic equations in his book Ars Magna, with one case of this solution

communicated to him by N. Tartaglia. He noted the existence of so-called imaginary numbers, but did not describe

their properties. L. Ferrari (Italy, 15221565) solved the quartic equation, which was mentioned in the book Ars

Magna by his teacher G. Cardano. R. Descartes (1637) suggested the name "imaginary" for nonreal numbers like

1 + -1 . J. Wallis (1685) in De Algebra tractates published the idea of the graphic representation of complex

numbers. J. Bernoulli (1702) used imaginary numbers. R. Cotes (1714) derived the formula:

cosHL + sinHL,which in 1748 was found by L. Euler and hence named for him.

A. Moivre (1730) derived the well-known formula HcosHxL + sinHxLLn cosHn xL + sinHn xL ; n N, which bearshis name.

Investigations of L. Euler (1727, 1728) gave new imputus to the theory of complex numbers and functions of

complex arguments (analytic functions). In a letter to C. Goldbach (1731) L. Euler introduced the notation for the

base of the natural logarithm 2.71828182 and he proved that is irrational. Later on L. Euler (17401748)

found a series expansion for z, which lead to the famous and very basic formula connecting exponential and

trigonometric functions cosHxL + sinHxL x (1748). H. Khn (1753) used imaginary numbers. L. Euler (1755)used the word "complex" (1777) and first used the letter i to represent -1 . C. Wessel (1799) gave a geometrical

interpretation of complex numbers.

As a result, mathematicians introduced the use of a special symbolthe imaginary unit that is equal to = -1 :

2 -1.

In the 19th century the conception and theory of complex numbers was basically formed. A. Buee (1804) indepen-

dently came to the idea of J. Wallis about geometrical representations of complex numbers in the plane. J. Argand

(1806) introduced the name modulus for x2 + y2 , and published the idea of geometrical interpretation of com-

plex numbers known as the Argand diagram. C. Mourey (1828) laid the foundations for the theory of directional

numbers in a little treatise.


The imaginary unit was interpreted in a geometrical sense as the point with coordinates 80, 1< in the Cartesian(Euclidean) x, y plane with the vertical y axis upward and the origin 80, 0 0 R,where r = x2 + y2 is the distance between points 8x, y< and 80, 0 0,

which describe the main characteristics of the complex number z x + ythe so-called modulus (absolute value)

r, the real part x, the imaginary part y, and the argument .

The Euler formula cosHL + sinHL allows the representation of the complex number z, using polar coordi-nates Hr, L in the more compact form:z r ; r R r 0 @0, 2 L.It also allows the expression of the logarithm of a complex number through the formula:

logHzL logHrL + ; r R r > 0 R.Taking into account that the cosine and sine have period 2 , it follows that has period 2 :

+2 H+2 L cosH + 2 L + sinH + 2 L cosHL + sinHL .Generically, the logarithm function log HzL is the multivalued function:logHzL logHrL + H + 2 kL ; r R r > 0 R k Z.For specifying just one value for the logarithm logHzL and one value of the argument for a given complex numberz, the restriction - < is generally used for the argument .


C. F. Gauss (1831) introduced the name "imaginary unit" for -1 , suggested the term complex number for

x + y, and called x2 + y2 the norm, but mentioned that the theory of complex numbers is quite unknown, and in

1832 published his chief memoir on the subject. A. Cauchy (17891857) proved several important basic theorems

in complex analysis. N. Abel (18021829) was the first to widely use complex numbers with well-known success.

K. Weierstrass (1841) introduced the notation z for the modulus of complex numbers, which he called the absolutevalue. E. Kummer (1844), L. Kronecker (1845), Scheffler (1845, 1851, 1880), A. Bellavitis (1835, 1852), Peacock

(1845), A. Morgan (1849), A. Mobius (17901868), J. Dirichlet (18051859), and others made large contributions

in developing complex number theory.

Definitions of classical constants and the imaginary unit

Classical constants and the imaginary unit include eight basic constants: golden ratio , pi , the number of radians

in one degree , Euler number (or Euler constant or base of natural logarithm) , Euler-Mascheroni constant (Euler

gamma) , Catalan number (Catalan's constant) C, Glaisher constant (Glaisher-Kinkelin constant) A, Khinchin

constant (Khintchine's constant) K, and the imaginary unit . They are defined by the following formulas:

1

2K1 + 5 O expIcsch-1H2LM

4 k=0

H-1Lk2 k + 1

180

k=0

1

k !

limn

k=1

n 1

k- logHnL

C k=0

H-1LkH2 k + 1L2

A exp1

12- H-1L

K k=1

1 +1

k Hk + 2Llog2HkL

-1 .

The number is the ratio of the circumference of a circle to its diameter.

Connections within the group of classical constants and the imaginary unit and with other function groups

Representations through functions


The classical constants , , , , , C, A, and the imaginary unit can be represented as particular values of

expressions that include functions (Fibonacci F, algebraic roots, exponential and inverse trigonometric functions,

complete elliptic integrals KHzL and EHzL, dilogarithm Li2HzL, gamma function GHzL, hypergeometric functions pF q,pFq, Meijer G function Gp,q

m,n, polygamma function HzL, Stieltjes constants n, Lerch transcendent FHz, s, aL, andHurwitz and Riemann zeta functions Hs, aL and HsL), for example:

12

K 5 F1 + 5 F12 - 4 O 4 J4 tan-1J 15 N - tan-1J 1239 NN 145 J4 tan-1J 15 N - tan-1J 1239 NN 0F 0H

2-1 K 5 F +5 F

2 + 4 cosH L O1 ; R > 0

4 tan-1J 12

N + 4 tan-1J 13

N 8 tan-1J 1

3N + 4 tan-1J 1

7N

4 tan-1J 12

N + 4 tan-1J 15

N + 4 tan-1J 18

N

145

Jtan-1J 12

N + tan-1J 13

NN 1

45J2 tan-1J 1

3N + tan-1J 1

7NN

1

45Jtan-1J 1

2N + tan-1J 1

5N + tan-1J 1

8NN

0F0H

exp Icsch-1H2LM 4 J6 tan-1J 18

N + 2 tan-1J 157

N +tan-1J 1

239NN

145

J6 tan-1 J 18

N + 2 tan-1 J 157

N +tan-1 J 1

239NN

G0,11,0

Iz; z2 - z - 1M2

-1 4 tan-1J 1

2N + 4 tan-1J 1

5N +

4 tan-1J 18

N 1

45 Jtan-1J 1

2N + tan-1J 1

5N +

tan-1J 18

NN z ;

4 J6 tan-1J 18

N + 2 tan-1J 157

N+ tan-1J 1

239NN

145

J6 tan-1 J 18

N + 2 tan-1 J 157

N+ tan-1 J 1

239NN

log HL

88 tan-1J 128

N + 8 tan-1J 1443

N -20 tan-1J 1

1393N - 40 tan-1 J 1

11 018N

145

J22 tan-1J 128

N + 2 tan-1J 1443

N -5 tan-1J 1

1393N - 10 tan-1J 1

11 018NN

48 tan-1J 118

N + 12 tan-1J 170

N +20 tan-1J 1

99N + 32 tan-1 J 1

307N

145

J12 tan-1J 118

N + 3 tan-1J 170

N +5 tan-1J 1

99N + 8 tan-1J 1

307NN

4 Jtan-1J pq

N + tan-1J q-pp+q

NN ;p N+ q N+

145

Jtan-1J pq

N + tan-1J q-pp+q

NN ;p N+ q N+

2 KH0L 2 EH0L KH0L90

EH0L90

G J 12

N2 6 Li2H1L 1180 GJ 12 N2 1180 6 Li2H1LRepresentations through related functions

The four classical constants , , , and and the imaginary unit can sometimes be represented through other

classical constants and the imaginary unit by formulas such as the following:


2 cos J 5

N 1

2secJ 2

5N

12

cscJ 10

N

2 cosH36 L 1

2secH72 L

12

cscH18 L

5 + -

5

5 + -

5

5 cos-1 J 2

N -5 log 1

2 + 4 - 2

180 -

2

-1

2 1

k H-1Lk ; k Z

- logH-1L 2 logJ 1-

1+N

-

2

-1

2 1

k H-1Lk ; Z 1

36cos-1J

2N

- 36

log 12

+ 4 - 2

180

-90 k

180 -1

360 1

- 180

logH-1 1

90 logJ 1-

1+

-90 k

180 -1

360 1

180 k H-1Lk Z

-2

-1

2 1

k H-1Lk ; k Z

90 k k ; k Z180 -1

360 1

180 k H-1Lk ; k Z

-

2

-1

2 1

k H-1Lk ; Z -

logH-1L - 180 logH-1L -2

-1

2 1

k H-1Lk ; k ZThe best-known properties and formulas for classical constants and the imaginary unit

Values

first 50 digits number of digits computed in year

1.6180339887498948482045868343656381177203091798057 2002, near 3 141 000 000 digits

3.1415926535897932384626433832795028841971693993751 December 2002, near 1 241 100 000 000 digits

0.017453292519943295769236907684886127134428718885417 December 2002, near 1 241 100 000 000 digits

2.7182818284590452353602874713526624977572470936999 2003, near 50 100 000 000 digits

0.57721566490153286060651209008240243104215933593992 December 2006, near 116 580 000 digits

C 0.91596559417721901505460351493238411077414937428167 2002, near 201 000 000 digits

A 1.2824271291006226368753425688697917277676889273250 December 2004, near 5000 digits

K 2.6854520010653064453097148354817956938203822939944 1998, near 110 000 digits

The imaginary unit satisfies the following relation:

2 -1.

Evaluation of specific values


For evaluation of the eight classical constants , , , , , C, A, and K, Mathematica uses procedures that are

based on the following formulas or methods:

basic formula or method

Karatsuba's modifications of Newton's methods for evaluations z Jbecause 12

J1 + 5 NN 1

12 k=0 H-1Lk H6 kL! H545 140 134 k+13 591 409L

k!3 H3 kL! I640 3203Mk+12

180

limn Jk=0n 1k! N limx

1

k=0 xkHk!L2 k=0 i=1k xki Hk!L2 - logHxL2

C C 8

logI 3 + 2N + 38

k=0 k!2H2 kL! H2 k+1L2A A limn exp

1

12logH2 L -

1

2 2 21-an log8H10L+1q j=02 an log8H10L+1q-1 1H j+1L2 logH2 H j + 1LL H-1L j k=0j-an log8H10L+1q an log8H10L + 1qk - 2an log8H10L+1q + 12

K K limn expJ 1logH2L m=1en log4H10Lu+1 1m HH2 mL - 1L k=12 m-1 H-1Lk+1k NThe formula for 1 is called Chudnovsky's formula.Analyticity

The eight classical constants , , , , , C, A, and K are positive real numbers. The constant is a quadratic

irrational number. The constants , , and are irrational and transcendental over Q. Whether C and are irrational

is not known.

The imaginary unit is an algebraic number.

Series representations

The five classical constants , , , C, and K have numerous series representations, for example, the following:

4 k=0

H-1Lk2 k + 1

4

2 k=0

1

2 k + 1 H-1Lf k2 v 3 3

k=0

H-1Lk3 k + 1

- logH2L 3

2 logH2L + 4 k=0

1

k + 1 H-1Lf k+12 v

k=0

1

16k -

2

8 k + 4-

1

8 k + 5-

1

8 k + 6+

4

8 k + 1

k=0

H-1Lk4k

2

4 k + 2+

1

4 k + 3+

2

4 k + 1

5

45

k=0

2 k

k

1

2 k + 1F2 k+1 16

-k 4 k=1

tan-11

F2 k+1


k=1

3k - 1

4k Hk + 1L

2 k=0

H2 k - 1L !!H2 k + 1L H2 kL !! 3 2 k=1

k !2

k2 H2 kL ! 6 k=0 H2 kL !!

H2 k + 1L !! 22 k+2 Hk + 1L an + bn

k=1

kn

2 k

k

;

n 1 2 3 4 5 6 7 8 9 10

an -3 3 -18 3

5-

135 3

37-

432 3

119-

243 3

67-

23 814 3

6565-

42 795 3

11 797-

2 355 156 3

649 231-

48 314 475 3

13 318 583-

365 306 274 3

100 701 965

bn9

23 27

103 81

743 81

2383 81

9383 243

13 130 3 81

23 5943 729

1 298 4623 2187

26 637 166 3 2187

201 403 930 3

cn k=1

1

k2 n

1

2 n ;n 1 2 3 4 5 n ; n N+cn 6 3 1014 3 3516 338 514 1418 3 385110 H-1Ln-1 H2 nL!

22 n-1 B2 n

1

2 n

cn k=1

H-1Lk-1k2 n

1

2 n ;n 1 2 3 4 5 n ; n N+cn 2 3 2 J 57 N14 3 J 3531 N16 256 3 2 J 7127 N18 338 514 J 5573 N110 2910 3 H-1Ln H2 nL!22 n-1 B2 nJ 12 N

1

2 n

cn k=0

1

H2 k + 1L2 n1

2 n ;n 1 2 3 4 5 n ; n N+cn 2 2 2 614 2 1516 2 314 J 7017 N18 2 J 3531 N110 325 H-1Ln-1 2 H2 nL!I22 n-1M B2 n

1

2 n

cn k=0

H-1LkH2 k + 1L2 n-1

1

2 n-1 ; n 1 2 3 4 5 n ; n N+

cn 4 2 223 2 J 35 N15 245 2 J 561 N17 257 327 2 J 7277 N19 289 329 J H-1Ln-1 22 n H2 n-2L!E2 n-2 N1

2 n-1


C K

k=0 1k! logH2L2 + 1logH2L k=2 H-1Lk logHkLk C 2 k=0 1H4 k+1L2 - 28 K exp J 1logH2L k=2 log k=0 2 k+1H2 kL! k=2 JlogJ1 - 1k N + 1k N + 1 C 28 - 2 k=0 1H4 k+3L2 K expJlogH2L + 12 logH2 2 k=0 k+1H2 k+1L! k=2 H-1Lkk HkL C 2 logH2L - 132 k=0 H2 k+1L!216k k!4 Hk+1L3 K expK 1logH2L k=2 H-1 k 1

2 k=0 k+1k! 1 - k=2 HkL-1k C 2 logH2L - 132 k=0 H2 k+1L!216k k!4 Hk+1L3 K expJ 1logH2L Jlog2H2L

k=0 3-4 k2H2 k+1L! logH2L - k=1 H2 k+1L4k H2 k+1L C 2 logH2L + k=0 H-1Lk2 k+1 HHk + 1L + L K expJ 1logH2L J 26 - 12 k=0 H3 kL2+1H3 kL! C 4 logH2L + k=0 H-1Lk2 k+1 JJk + 32 N + N K expJ 1logH2L k=1 H2 2

3k=0 Hk+3Lk mod 22k mod 2 k! C 1 - k=1 k H2 k+1L42 k 18 k=2 k2k Jk + 1, 34 N

logHAL 12

k=0

1

k + 1 j=0

k H-1L j+1 kj

H j + 1L2 logH j + 1L + 18

.

Product representations

The four classical constants , , , and A can be represented by the following formulas:

A

2 k=1 4 k2H2 k-1L H2 k+1L 2 k=0 1

GJ 12

+2k+1N 22k+1 GJ 1

2+ 2kN2 2-k-1

log n=0 k=0n Hk + 1LH-1Lk+1n

k

1

n+1

A

2 k=2 secJ 2k N 3 k=0 secJ 12 2k N

2 j=1 k=02 j-1-1 J 2 k+2 j+22 k+2 j+1 N1

2 j A 29

k=1 2 k=1 J1 + 2k NH-1Lk+1 k k=1 k-

HkLk

6 k=1 I1 - pk-2M-1 ; pk PIntegral representations

The five classical constants , (and ), , C, A, and K have numerous integral representations, for example:


C A

2 0 1t2+1 t -0-t logHtL t C 14 0 t2 tt+1 t A 2736

6 exp J 2

3 012logH 4 01 1 - t2 t -01logH-logHtLL t C 12 0t sechHtL t 12 0

2 t

sinHtL t 2 01 1

1-t2 t -01logJlogJ 1t NN t C -01 logHtLt2+1 t -01 1t2+1 log 1-t2 t

2 0 cosHtLt2+1 t -01 1-

1

t -t

t H1-tL t C -2 0

4 logH2 sin HtLL t 2 04 logH2 cosHtLL t 01 1--t--1tt t C -0

4 logHtan HtLL t 04 logHcotHtLL t 0J 1t-1 - 1t t N t C 01 tan-1HtLt t 0

2 sinh-1HsinHtLL t 2 0 -t2 --tt t C 0

2 sinh-1Hcos HtLL t 02 csch-1HcscHtLL t

- 0 -t --t t t ;

> 0 > 0C 02 csch-1 Hsec HtLL t

-- t t-t t C 14 01 KHtLt t 12 01KIt2M t 1

2+ 2 0 tIt2+1M I2 t-1M t C 34 0

6 t

sinHtL t + 8 log I2 + 3 N -0 1t JcosHtL - 1t2+1 N t C - 24 01Jt - 12 N sec H tL t 01J 1logHtL + 11-t N t C 0

2 t cscHtLcosHtL+sinHtL t - 4 log H2L

01J 1logH1-tL + 1t N t C 4 log H2L - 12 01 logH1-tLt Ht+1L tC

8log H2L - 01 logH1-tLt2+1 t

cn 0

sinnHtLtn

t ;n 1 2 3 4 5 6 n ; n N+cn 2 2

8

33 384

115

40

11 2n n k=0f n-12 v H-1Lk Hn-2 kLn-1k! Hn-kL!

The following integral is called the Gaussian probability density integral:

2 0-t2 t.The following integrals are called the Fresnel integrals:

2 2 0sinIt2M t

2 2 0cosIt2M t.Limit representations

The six classical constants , , , , A, and K have numerous limit representations, for example:


1 + 1 + 1 + 1 + limn 24 n n 2 nn2

limz0 Hz + 1L1z lims1 JHsL - 1s-1

limn zn ;zn+1 = 1 + zn z0 1

limn4

n2 k=0n n2 - k2 limz zz!1z lims Js - GJ 1s N

limF

F-1 4 limn k=1f n v n-k2n limn k=1n n2+kn2-k limx1+ Ik=1 Ik- limn

24 n+1 n!4

H2 n+1L H2 nL!2 limn J2 k=0n nkk! N1n limn HHn-1 - log limn

2 H2 nL!!2H2 n+1L H2 n-1L!!2 limz J zzHz-1Lz-1 - Hz-1Lz-1Hz-2Lz-2 N lim0 HliH xL -

logHLL - log 0 limn

n!2 Hn+1L2 n2+n2 n2 n

2+3 n+1 limz

4 zHzLz+11z limn KlogHpnLk=1n logIpkMpk-1 O P

16 limn Hn + 1L k=1n k2H2 k+1L2 limn Ik=1HnL pkM1

pn ;pn prime HnL

limnk=1n Jb nk r-

n

limx0 JEiHlogHxEiHlogHx + 1LLlogJ1 - 1

xN + N

Continued fraction representations

The four classical constants , , , and C have numerous closed-form continued fraction representations, for

example:

1 + KkH1, 1L1 1 + 11 +

1

1 +1

1 +1

1 +

3 + KkIH2 k - 1L2, 6M1 3 + 16 +

9

6 +25

6 +49

6 +81

6 +121

6 +


2 1 -

1

3 + KkI-Ik - H-1LkM Ik - H-1Lk + 1M, 2 + H-1LkM1 1 -1

3 -6

1 -2

3 -20

1 -12

3 -42

1 -30

3 -

4

1 + KkIk2, 2 k + 1M1 1 + 1

3 +4

5 +9

7 +16

9 +25

11 +36

13 +

2 + Kk 1,2 Hk + 1L

3

1

2I1-H-1LHk+2L mod 3M

1

2 +1

1 +1

2 +1

1 +1

1 +1

4 +1

1 +

1 +1

KkHk, kL1 2 +2

2 +3

3 +4

4 +5

5 +6

6 +7

7 +

1 +2

1 + KkH1, 4 k + 2L1 1 +2

1 +1

6 +1

10 +1

14 +1

18 +1

22 +1

26 +


C 1 -1

2 3 + KkKJ2 f k+12 vN2, 3Hk-1L mod 2O1

1 -1 2

3 +4

1 +4

3 +16

1 +16

3 +36

1 +36

3 +

C 1

2+

1

1 + 2 KkJ 116 JIH-1Lk - 1M2 Hk + 1L2 + 2 I1 + H-1LkM k Hk + 2LN, 12 N1.

1

2+

1 21

2+

1

1

2+

2

1

2+

4

1

2+

6

1

2+

9

1

2+

12

1

2+

.

Functional identities

The golden ratio satisfies the following special functional identities:

2 - - 1 0

1 +1

1 +

1

1 + 1

1 +1

1 + 11+

1

1 +1

1 + 11+

1

1+1

n n-1 + n-2 ; n N+

2+

H1+L 1+2 2+ .Complex characteristics

The eight classical constants (, , , , , C, A, and K) and the imaginary unit have the following complex

characteristics:

Abs Arg Re Im Conjugate Sign

Arg HL 0 Re HL Im HL 0 sgn HL 1 1 Arg HL

2Re HL 0 Im HL 1 - sgn HL ; 8, , , , , C, A, K

pi_1

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