Sunday, March 18, 2018


March 18, 2018 Sunday

Bedtime Story 


The Elusive Constant 𝒆


Last night we were dealing with exponential functions where we saw that the constant of proportionality of this relationship is the natural logarithm of base b.

d/dx(bx) =  bxloge(b)
    
The constant e is the unique base for which the constant of this proportionality is 1.

d/dx(ex) = exloge(e) = ex
    
From the study of this exponential function, Huygens saw the emergence of logarithm to base 10 of e and he calculated its value to 17 decimal places.

Yet even Huygens did not get the number e as an independent constant on which entire logarithmic tables can be based upon.

In 1668 a German mathematician by the name of Nicholas Mercator came out with a book on logarithms that he called Logarithmo-technia in which he describes a series that is obviously now called the Mercator series.

The Mercator series goes like this:

ln(1+x) = x – x²/2 + x³/3 – x⁴/4 + x⁵/5  

It was in this book by Mercator that the term natural logarithm for the first time came on print though of course, since the language of science of those times was either Latin or French, the term that is found in the original untranslated book is ‘log naturalis’.

Yet that number e once again fails to appear on its own and stays hidden though it is being referred indirectly again and again and yet so far, none has given it its due exclusivity that it deserves.

Surprisingly enough, when the discovery of the mathematical constant e came, it came through the study of compound interest as we saw earlier, despite its strong relationship with logarithms and constantly getting referred indirectly in logarithmic works of many mathematicians.

Even bigger oddity or rather incongruity about the discovery of the number e is that even when Jacob Bernoulli did discover it independently and on its own right through his compounding problem, he totally missed out on its deep connection with the logarithms which in those days were equivalent to today’s super computers.

Today we see logarithm as the inverse operation to exponentiation, just as division is seen as inverse of operation.

So if 5 raised to the power of 3 is equal to 125, then the logarithm to base 5 of 125 is 3.

So 53 = 125

Then log5125 = 3      

The beauty is that since the exponentiation function allows any positive real number to be raised to any real power, then by the definition of logarithm it also means that the logarithm can be calculated for any two positive real numbers b and x where b is not equal to 1.

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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