Why isn't sum of logs == log of product?

3 次查看（过去 30 天）
James Mooney
James Mooney 2022-5-3
回答： Image Analyst 2022-5-3
Why am I getting false for this when the answers are equal?
>> log(3) + log(4) == log(3*4)
ans =
logical
0
>> log(3) + log(4)
ans =
2.4849
>> log(3*4)
ans =
2.4849

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回答（2 个）

Image Analyst
Image Analyst 2022-5-3
the cyclist
the cyclist 2022-5-3
编辑：the cyclist 2022-5-3
Ran in:
They are equal to within double precision:
log(3) + log(4) - log(3*4)
ans = -4.4409e-16
There are many places on this forum that discuss this in more detail, e.g. this question/answer.

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