From: "mrkn (Kenta Murata)" <muraken@...>
Date: 2013-07-03T23:44:37+09:00
Subject: [ruby-core:55781] [ruby-trunk - Bug #6862] BigMath.exp negative exponent


Issue #6862 has been updated by mrkn (Kenta Murata).


mame (Yusuke Endoh) wrote:
> So phasis68 should have a commit bit, as I said. ;-)

+1
----------------------------------------
Bug #6862: BigMath.exp negative exponent
https://bugs.ruby-lang.org/issues/6862#change-40276

Author: karatedog (F��ldes L��szl��)
Status: Closed
Priority: Normal
Assignee: mrkn (Kenta Murata)
Category: 
Target version: next minor
ruby -v: ruby 1.9.3p260 (2012-08-09 revision 36669) [i686-linux]
Backport: 1.9.3: REQUIRED, 2.0.0: DONE


Ruby 1.9.3 BigMath.exp accepts Fixnum for exponent but silently treats negative exponents as positive:
1.9.3p260 :009 > BigMath.exp(3, 10)
 => #<BigDecimal:9be2ce8,'0.2008553692E2',18(72)> 
1.9.3p260 :010 > BigMath.exp(-3, 10)
 => #<BigDecimal:9bd8e50,'0.2008553692E2',18(45)>

Converting the exponent parameter to BigDecimal solves the problem:
1.9.3p260 :011 > BigMath.exp(BigDecimal(-3), 10)
 => #<BigDecimal:9bd1420,'0.4978706837E-1',18(45)> 





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