Mathematics Dictionary
Dr. K. G. Shih
The Story of Pi
Questions
Symbol Defintion
Sqr(x) = Square root of x
Q01 |
- Series : arctan(x) = x - x^3/3 + x^5/5 - x^7/7 + ....
Q02 |
- Series : (pi)^2 = 6*(1 + 1/(2^2) + 1/(3^2) + ......)
Q03 |
- Series : (pi)^2 = 8*(1 + 1/(3^2) + 1/(5^2) + ......)
Q04 |
- Archimedes polygon method to find pi
Q05 |
- Value of pi to 1000 decimal places
Q06 |
- Story of pi : Pi and computer
Q07 |
- Machine-like formula
Q08 |
- Reference
Answers
Q01. Series : arctan(x) = x - x^3/3 + x^5/5 - x^7/7 + ....
Series of pi
Since arctan(1) = pi/4
Hence pi/4 = 1 - 1/3 + 1/5 - 1/7 + .....
This series is simple but it coverge very slow
Gregory's series
pi/4 = 1 - 1/3 + 1/5 - 1/7 + ....
Go to Begin
Q02. Series : (pi)^2 = 6*(1 + 1/(2^2) + 1/(3^2) + 1/(4^2) + .....
Keywords
1. To prove it, we use series of sin(x)
2. We also need equation of theory
Proof
Sin(x) = x - (x^3)/(3!) + (x^5)/(5!)- (x^7)/(7!) + ....
If sin(x) = 0, the roots are r0 = 0, r1 = pi, r2 = 2*pi, r3 = 3*pi, ....
Hence r1, r2, r3, ... are roots of 1 - (x^2)/6 + (x^4)/120 - ..... = 0
Let x^2 = u,
Then the equation becomes 1 - u/6 + (u^2)/120 - .... = 0
The roots of equation : u1 = (pi)^2, u2 = (2*pi)^2, u3 = (3*pi)^2
Equation theory
Equation : a*x^n + b*x^(n-1) + ..... + p*x + q = 0
Roots are x1, x2, x3, ....
Coefficient of x and roots : 1/x1 + 1/x2 + 1/x3 + ..... = p/q
Hence coefficient and roots u
1/u1 + 1/u2 + 1/u3 + ..... = -(-1/6)/1
1/(pi^2) + 1/((2*pi)^2) + 1/((3*pi)^2) + 1/((4*pi)^2) + .... = 1/6
Multiply (pi)^2 on both sides
1 + 1/(2^2) + 1/(3^2) + ..... = ((pi)^2)/6
Go to Begin
Q03. Series : (pi)^2 = 8*(1 + 1/(3^2) + 1/(5^2) + 1/(7^2) + ....
Keywords
1. To prove it, we use series of cos(x)
2. We also need equation of theory
Proof
cos(x) = 1 - (x^2)/(2!) + (x^4)/(4!)- (x^6)/(6!) + ....
If cos(x) = 0, the roots are r1 = pi/2, r2 = 3*pi/2, r3 = 5*pi/2, ....
Hence r1, r2, r3, ... are roots of 1 - (x^2)/2 + (x^4)/24 - ..... = 0
Let x^2 = u,
Then the equation becomes 1 - u/2 + (u^2)/24 - .... = 0
The roots of equation : u1 = (pi/2)^2, u2 = (3*pi/2)^2, u3 = (5*pi/2)^2
Equation theory
Equation : a*x^n + b*x^(n-1) + ..... + p*x + q = 0
Roots are x1, x2, x3, ....
Coefficient of x and roots : 1/x1 + 1/x2 + 1/x3 + ..... = p/q
Hence coefficient and roots u
1/u1 + 1/u2 + 1/u3 + ..... = -(-1/2)/1
1/((pi/2)^2) + 1/((3*pi/2)^2) + 1/((5*pi/2)^2) + .... = 1/2
Multiply (pi/2)^2 on both sides
1 + 1/(3^2) + 1/(5^2) + ..... = ((pi/2)^2)/2 = ((pi)^2)/8
Go to Begin
Q04. Archimedes polygon method to find pi
Formula based Archimedes polygon method
pi = C*sin(A)
Where C = (2^n)/2 and A = 360/(2^n)
Where 2^n is the number of sides of polygon
Example 1 : n = 3
pi = ((2^3)/2)*sin(45) = 4*Sqr(2)/2 = 2*Sqr(2)
Example 1 : n = 5 and use half angle formula
pi = ((2^5)/2)*sin(360/32)
= 16*Sqr((1 - cos(360/16))/2)
= (16/Sqr(2))*Sqr(1 - cos(360/16))
= (16/Sqr(2))*Sqr(1 - Sqr(1 + cos(360/8))/2))
= 8*Sqr(2 - Sqr(2 + Sqr(2))) = 3.121445
Go to Begin
Q05. Value of pi to 1000 decimal places
Pi Value to 1000 decimal place
pi = 3.
1415926535 8979323846 2643383279 5028841971
6939937510 5820974944 5923078164 0628620899
8628034825 3421170679 8214808651 3282306647
0938446095 5058223172 5359408128 4811174502
8410270193 8521105559 6446229489 5493038196
4428810975 6659334461 2847564823 3786783165
2712019091 4564856692 3460348610 4543266482
1339360726 0249141273 7245870066 0631558817
4881520920 9628292540 9171536436 7892590360
0113305305 4882044652 1384146951 9415116094
3305727036 5759591953 0921861173 8193261179
3105118548 0744623799 6274956735 1885752724
8912279381 8301194912 9833673362 4406566430
8602139494 6395224737 1907021798 6094370277
0539217176 2931767523 8467481846 7669405132
0005681271 4526356082 7785771342 7577896091
7363717872 1468440901 2249534301 4654958537
1050792279 6892589235 4201995611 2129021960
8640344181 5981362977 4771309960 5187072113
4999999837 2978044951 0597317328 1609631859
5024459455 3469083026 4252230825 3344685035
2619311881 7101000313 7838752886 5875332083
8142061717 7669147303 5982534904 2875546873
1159562863 8823537875 9375195778 1857780532
Go to Begin
Q06. Story of pi
Pi = 3.141592....
(1) To 1000 decimal place : see Computer Math p47
(2) Story of Pi (See Computer Math Chapter 6)
(3) New record : 106 billion decimal places (Genume 2002) by Janpanese scientists
Pi and Computers
1949 ENIAC was used to compute Pi to 2037 decimal places.
1961 IBM 7090 computed Pi to 100000 decimal places by Shanks and Wrench.
1966 IBM Stretch supercomputer computed pi to 250000 decimal places.
1983 Pi is computed to 16 million decimal places.
1987 Pi is calculated to 134 million decimal places
by Yasumasa Kanada of the University of Tokoyo
using Nippon Electronic SX-2 supercomputer
1989 Pi calculated to 1;011;196;691 decimal places
by David and Gregory Chudnovsky at the Columbia University; New York
The calculation was performed twice on an IBM
3090 mainframe and on a Cray-2 supercomputer; and the
results matched.
1991 Brothers David and Gregory Chudnovsky
use a formula of their discovery and low budget supercomputer
to compute pi to 2.1 billion decimal places
References
Augarten; Stan 1984
Bit by bit : an illustrated history of computers.
Ticknor and Fields; New york; 324p.
Freedman; Allan 1989
The computer glossary; 4th edition. AMACOM; Division of
American Management Association; 776p.
Ralston; Anthony and Reilly; Edwin D. 1993
Encyclopedia of computer science. Third edition. Van
Nostrand Reinhold; New York; 1558p.
Taylor; C. F.; Jr. 1988
Master handbook of microcomputer languages; 2nd
edition; Tak Book; Inc.; Blue Ridge Summit; PA; U.S.A. 499p.
Microsoft Press; 1991
Computer dictionary : The comprehensive standard for
business; school; library and home. Microsoft Press. 392p.
Go to Begin
Q07. Machine-like formula
Machine-like formula
1. Euler's formula : pi/4 = arctan(1/2) + arctan(1/3)
2. Hermann's formula : pi/4 = 2*arctan(1/2) - arctan(1/7)
3. Hutton's formula : pi/4 = 2*arct(1/3) + arctan(1/7)
Go to Begin
Q08. Reference
Book
Story of pi
Chapter 6, p47 - p54
Computer Mathematics by Dr. Keh-Gong Shih
Published by National Institute For Compilation and Translation
Taipei, Taiwan. 1993. pp 262
Story of e, i, pi
Euler
: Introduced e, i, and pi to mathematics
Story of e
>
1. Select number theory
2. Select constant
3. Select e
Story of PI
1. Select number theory
2. Select constant
3. Select pi
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Q08. Answer
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Q09. Answer
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Q10. Answer
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