Stirling's approximation: Difference between revisions

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m (New page: James Stirling (1692-1770, Scotland) :<math>\left.\ln N!\right. = \ln 1 + \ln 2 + \ln 3 + ... + \ln N</math> :<math> ~= \sum_{k=1}^N \ln k</math> :<math>~\approx \int_1^N \ln x dx</ma...)
 
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:<math>\ln N! \approx  N \ln N -N</math>
:<math>\ln N! \approx  N \ln N -N</math>
[[Category: Mathematics]]

Revision as of 11:56, 27 February 2007

James Stirling (1692-1770, Scotland)

lnN!=ln1+ln2+ln3+...+lnN


=∑k=1Nlnk


≈∫1Nlnxdx


=[xlnx−x]1N


=NlnN−N+1

Thus, for large N

lnN!≈NlnN−N