Friday, July 27, 2012

As History of Mathematics, Sigh ....

Mini-Series On Classical Mathematics: 
As History of Mathematics ... Sigh ...
Absolute and Relative Roman Numerals
Two is Still Not a Number With any Square Root
Now, for the essay: 

Terry Jones may well have intended blasphemy when he was doing Life of Brian - whether the result was so or not for each viewer. That is despicable enough. But now he stoops to something which even his own crew despise: dishonesty in history. He makes a program which I watch on youtube in two videos. I cannot help noting a few dishonesties in it, which substantiate this observation:

"There is a share for women and there is a share for men."

It is quite true that some Christian monarchies - notably Germanic ones - did not insist on this, when it came to dividing land ownership. Roman law however did so, as long as the land ownership was mere land ownership - for among the Germanic people's it usually idrectly involved political power over those living on the land. Christianity as such did neither.

However, when people in Baghdad were counting on their fingers, that was not a bad number system. Only problem is if gesture is too fast and you start quarrelling about what exact middle finger to take or what finger to bend. You see, counting on fingers was not a one to ten count, you could count from 1 to 99 on one hand and from 100 to 9900 on the other. It is still used in Persia.*

So, Arabic numerals - borrowed from India under Al-Mansoor, according to the program I am watching - were good because they exactly like Roman ones would have allowed the parts of each algorithm (we can thank an Arabic mathematician called Al-Khwaresmi for that word, it means a setup like when you make the part operations in a certain order, like putting two lines of numbers on top of each other, then adding numbers that are in same position, then shifting possible ones - if sum is 10 or above - to the left on top of the next greater position, and so on), whereas watching someone else's fingers is a matter for sleight of hand between dishonest persons.

A little earlier, Terry Jones had claimed that Indian mathematicians had using the Arabic er ... Hindoostani numerals "calculated" that the earth spins on its axis and that it also moves around the sun. While it is quite possible they had arrived at that wild guess, it is equally certain that doing exact mathematics was not the key issue for arriving at it. Simplifying calculations and wanting to simplify them even more may have been part of the preference for the heliocentric system (which allows mars and venus to move with simply circular or elliptical movements rather than compound movements, around earth each day, the one that would take them around the zodiak each year with the sun except for that third one which moves them around the sun too and therefore deflects the zodiakal circles into non-yearly curly orbits that look more funny than easy to calculate).

And why would Indians have wanted to calculate heavenly movements with ease? Same motive as Kepler: they were astrologers and sought their earthly happiness in the movements of the stars.

And in the next video, he makes this test where one sorobanist and one banker using Arabic numerals arrive at different results at same rate of interest (10 pounds, 1 year, 1/2 percent per month), but not as he claims because the sorobanist rounds up to whole pennies, that is not necessary if she got it right, but because the banker added a compound interest - i e previous interest capitalised already before the lapse of the year. Which was not exactly what Terry had told the two to do.

If he had, and if the banker calculated correctly, they each would have concluded that after one year the compound interest would yield a total of 10 pounds and 62 decimal pennies. There were enough rows on her soroban to arrive at that.

Here are the videos: part 1 and part 2. They are funny unless you know the real story. A bit like Life of Brian. Some people just never learn ...

Hans-Georg Lundahl
BpI, G. Pompidou
Day after St Anne

*Link on finger calculus:

To 'read' the numbers or letters, the left hand can be divided into two parts – thumb and forefinger represent the 10s, and the remaining fingers numbers 1-9.

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