From: "naruse (Yui NARUSE)" <naruse@...>
Date: 2012-08-20T16:54:36+09:00
Subject: [ruby-core:47245] [ruby-trunk - Bug #6862][Assigned] BigMath.exp negative exponent


Issue #6862 has been updated by naruse (Yui NARUSE).

Status changed from Open to Assigned
Assignee set to mrkn (Kenta Murata)


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Bug #6862: BigMath.exp negative exponent
https://bugs.ruby-lang.org/issues/6862#change-28937

Author: karatedog (F��ldes L��szl��)
Status: Assigned
Priority: Normal
Assignee: mrkn (Kenta Murata)
Category: 
Target version: 1.9.3
ruby -v: ruby 1.9.3p260 (2012-08-09 revision 36669) [i686-linux]


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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