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Diffstat (limited to 'spec/ruby/core/math/lgamma_spec.rb')
-rw-r--r-- | spec/ruby/core/math/lgamma_spec.rb | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/spec/ruby/core/math/lgamma_spec.rb b/spec/ruby/core/math/lgamma_spec.rb new file mode 100644 index 0000000000..885a1b252c --- /dev/null +++ b/spec/ruby/core/math/lgamma_spec.rb @@ -0,0 +1,56 @@ +require File.expand_path('../../../spec_helper', __FILE__) + +describe "Math.lgamma" do + it "returns [Infinity, 1] when passed 0" do + Math.lgamma(0).should == [infinity_value, 1] + end + + platform_is_not :windows do + it "returns [Infinity, 1] when passed -1" do + Math.lgamma(-1).should == [infinity_value, 1] + end + end + + ruby_version_is "2.4" do + it "returns [Infinity, -1] when passed -0.0" do + Math.lgamma(-0.0).should == [infinity_value, -1] + end + end + + it "returns [log(sqrt(PI)), 1] when passed 0.5" do + lg1 = Math.lgamma(0.5) + lg1[0].should be_close(Math.log(Math.sqrt(Math::PI)), TOLERANCE) + lg1[1].should == 1 + end + + it "returns [log(2/3*PI, 1] when passed 6.0" do + lg2 = Math.lgamma(6.0) + lg2[0].should be_close(Math.log(120.0), TOLERANCE) + lg2[1].should == 1 + end + + it "returns an approximate value when passed -0.5" do + lg1 = Math.lgamma(-0.5) + lg1[0].should be_close(1.2655121, TOLERANCE) + lg1[1].should == -1 + end + + it "returns an approximate value when passed -1.5" do + lg2 = Math.lgamma(-1.5) + lg2[0].should be_close(0.8600470, TOLERANCE) + lg2[1].should == 1 + end + + it "raises Math::DomainError when passed -Infinity" do + lambda { Math.lgamma(-infinity_value) }.should raise_error(Math::DomainError) + end + + it "returns [Infinity, 1] when passed Infinity" do + Math.lgamma(infinity_value).should == [infinity_value, 1] + end + + it "returns [NaN, 1] when passed NaN" do + Math.lgamma(nan_value)[0].nan?.should be_true + Math.lgamma(nan_value)[1].should == 1 + end +end |