>perl -Mbignum -e "print log(10)"
NaN
>perl -v
This is perl 5, version 12, subversion 1 (v5.12.1) built for MSWin32-x
+86-multi-thread

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Works fine of course without bignum, producing 8.5 for the original question.

In reply to Re: What causes NaN when using bignum by wind
in thread What causes NaN when using bignum by Microcebus

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