Tuesday, March 27, 2018

March 27, 2018 Tuesday

Bedtime Story 


Note G of Ada Lovelace - 5


We are continuing tonight with Note G of Ada Lovelace.

“As however our object is not simplicity or facilitation of computation, but the illustration of the powers of the engine, we prefer selecting a formula below, marked (8).

This is derived in the following manner: –

If in the equation

\frac{x}{\epsilon^x-1}=1-\frac{x}{2}+\BB{1}\frac{x^2}{2}+\BB{3}\frac{x^4}{2\cdot 3 \cdot 4} + \BB{5}\frac{x^6}{2\cdot 3 \cdot 4 \cdot 5 \cdot 6}+\cdots 

Numbered as (4.)

(in which B1, B3… etc are the Numbers of Bernoulli), we expand the denominator of the first side in powers of x, and then divide both numerator and denominator by x, we shall derive

1=\left(1-\frac{x}{2}+\BB{1}\frac{x^2}{2}+\BB{3}\frac{x^4}{2\cdot 3\cdot 4}+\cdots\right)\left(1+\frac{x}{2}+\frac{x^2}{2\cdot 3}+\frac{x^3}{2\cdot 3\cdot 4}+\cdots\right) 

Numbered as (5.)

If this latter multiplication be actually performed, we shall have a series of the general form

1 + D1x + D2x2 + D3x3 + …                             (6.)

In which we see, first, that all the coefficients of the powers of x are severally equal to zero; and secondly, that the general form for D2n, the coefficient  of the 2n+1th term (that is of x2n and even powers of x), is the following:-

 
     
Numbered as (7.)

Multiplying every term by (2.3…2n) we have

 

Numbered as (8.)

Which it may be convenient to write under the general form:-

0 = A0 + A1B1 + A3B3 + A5B5 +…+ B2n-1                    (9.)

A1, A3 etc being those functions of n which respectively belong to B1, B3 etc.

We might have derived a form nearly similar to (8.), from D2n-1 the coefficient of any of power of x in (6.), but the general form is a little different for the coefficients of the odd power, and not quite so convenient.

On examining (7.) and (8.), we perceive that, when these formulae are isolated from (6.), whence they are derived, and considered in themselves separately and independently, n may be any whole number whatever; although when (7.) occurs as one of the D’s in (6.), it is obvious that n is then not arbitrary, but is always a certain function of the distance of that D from the beginning.”

Stay tuned to the voice of an average story storytelling chimpanzee or login at http://panarrans.blogspot.com
                              
Good night mon ami and my fellow cousin ape.
                           
  
                

             












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Another great educator and a teacher that I am aware of is Professor Subhashish Chattopadhyay in Bangalore, India.

While I narrate stories, Professor Subhashish an electronic engineer and a former professor at BARC, does and teaches real mathematics and physics.

He started the participation of Indian students at the International Physics Olympiad.

Do visit him here:


All his books can be downloaded for free through this link:


For edutainment and English education of your children, I recommend this large collection of Halloween Songs for Kids:



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