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I encountered a weird behaviour in Perl. The following subtraction should yield zero as result (which it does in Python):
print 7.6178E-01 - 0.76178
-1.11022302462516e-16
Why does it occur and how to avoid it?
P.S. Effect appears on “v5.10.0 built for x86_64-linux-gnu-thread-multi” (Ubuntu 9.04) and “v5.8.9 built for darwin-2level” (Mac OS 10.6)
It’s not that scientific notation affects the precision so much as the limitations of floating point notation represented in binary. See the answers to the perlfaq4. This is a problem for any language that relies on the underlying architecture for number storage.
If you need better number handling, check out the bignum pragma.