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I don't mean like log10(100)=2, that's obvious I mean like log10(20)~1.301, how does one figure that out, I asked my math teacher and he couldn't tell me..?

By the way, sorry I don't know how to make subscripts, and thanks.

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- #1

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I don't mean like log10(100)=2, that's obvious I mean like log10(20)~1.301, how does one figure that out, I asked my math teacher and he couldn't tell me..?

By the way, sorry I don't know how to make subscripts, and thanks.

- #2

berkeman

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My guess is that they used slide rules. Have you wiki'ed slide rules yet?

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Aren't slide rules based on logarithms? So wouldn't using them to calculate logs be rather circular?My guess is that they used slide rules. Have you wiki'ed slide rules yet?

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Integral

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But how were the tables figured out?

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Integral

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You asked "how people" calculated logs.

I have told you how PEOPLE did it.

I suspect that that table creators used something like a Taylor series polynomial, and lots of hand work.

EDIT:http://mathforum.org/library/drmath/view/52469.html"

I have told you how PEOPLE did it.

I suspect that that table creators used something like a Taylor series polynomial, and lots of hand work.

EDIT:http://mathforum.org/library/drmath/view/52469.html"

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Any logarithm can be computed by hand, using the Taylor series for [itex] \ln(1\pm x) [/itex] which converges for any real [itex] x<1 [/itex] and the logarithm's properties.

I don't mean like log10(100)=2, that's obvious I mean like log10(20)~1.301, how does one figure that out, I asked my math teacher and he couldn't tell me..?

By the way, sorry I don't know how to make subscripts, and thanks.

For example

[tex] \ln 243.5 =\ln 0.2435 + 3 \ln 10=\ln 0.2435 + 3 \ln 2 +3\ln 5=\ln 0.2435 + 12 \ln 2+3\ln 5/8 [/tex]

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Gib Z

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HallsofIvy

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John Napier, 1550 and 1617, is credited with the discovery of logarithms

http://johnnapier.com/table_of_logarithms_001.htm"

http://johnnapier.com/table_of_logarithms_001.htm"

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Integral

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The story I heard (Feynman?) is that they had a number crunching program written, but, for reasons I don't recall, the computer was not yet working. So they took the program which consisted of a stack of punch cards each with a single instruction (Some may recall these, I do) and passed it out to a number of people, probably with adding machines, each person did the calculation on their card and passed the result on to the next person.

A human computer.

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arildno

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Couldn't they just have plugged those numbers into von Neumann?The story I heard (Feynman?) is that they had a number crunching program written, but, for reasons I don't recall, the computer was not yet working. So they took the program which consisted of a stack of punch cards each with a single instruction (Some may recall these, I do) and passed it out to a number of people, probably with adding machines, each person did the calculation on their card and passed the result on to the next person.

A human computer.

That would have been simpler, faster and more reliable.

But perhaps more expensive..

- #13

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yeah, i have also read that von Neumann memorized the log tables. but how did he do it?

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