hexor's blog

log(a+b)
By hexor, 11 years ago, In English

if we know log(a) and log(b) how we can find log(a+b) approximately to real value?

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11 years ago, # |
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log(exp(log(a))+exp(log(b)))

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11 years ago, # |
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If a and b are close numbers, you can approximate using the following formula:

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For example, if a = b, then

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    11 years ago, # ^ |
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    why and need to be close for this formula to work?
    isn't (in addition to , ofcourse) sufficient?

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      11 years ago, # ^ |
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      This formula works OK, but if is some small number, you can remember its logarithm and thus approximate without calculator or paper — that was the point.

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