Math.Asinh is wrong with negative arguments
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Key: JRUBY-1592
URL: http://jira.codehaus.org/browse/JRUBY-1592
Project: JRuby
Issue Type: Bug
Components: Core Classes/Modules
Affects Versions: JRuby 1.x
Environment: Ubuntu Linux 7.10
ruby 1.8.5 (2007-11-20 rev 4842) [i386-jruby1.1b1]
Reporter: Vladimir Sizikov
MRI:
Math.asinh -2 => -1.44363547517881
Math.asinh -3 => -1.81844645923207
Jruby:
Math.asinh -2 => 1.4436354751788103
Math.asinh -3 => 1.8184464592320668
Looking at the asinh graph, it seems that the function never should be positive
on negative arguments.
Also, looking at the JRuby's tests
(externals/ruby_test/test/core/Math/class/tc_asinh.rb), they don't catch this
problem,
since they never test for values smaller than -1. Adding the test case for -2.0
would've exposed the problem as well.
This issue triggers a Rubinius spec test failure:
Math.asinh returns the inverse hyperbolic sin of the argument FAILED
Expected 1.8089166921396953 to be close to -1.8089166921397:
/opt/work/rubinius/./spec/core/math/../../spec_helper.rb:138:in
`should_be_close'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:11:in `should_be_close'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:9:in `it'
/opt/work/rubinius/spec/mini_rspec.rb:403:in `it'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:9:in `it'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:9:in `describe'
/opt/work/rubinius/spec/mini_rspec.rb:399:in `describe'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:4:in `describe'
/opt/work/rubinius/./spec/core/math/asinh_spec.rb:4:in `load'
last_mspec.rb:11:in `load'
last_mspec.rb:1:in `each'
last_mspec.rb:6:in `each'
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