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Diffstat (limited to 'spec/rubyspec/core/math/erf_spec.rb')
-rw-r--r-- | spec/rubyspec/core/math/erf_spec.rb | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/spec/rubyspec/core/math/erf_spec.rb b/spec/rubyspec/core/math/erf_spec.rb new file mode 100644 index 0000000000..1ea5693dfe --- /dev/null +++ b/spec/rubyspec/core/math/erf_spec.rb @@ -0,0 +1,44 @@ +require File.expand_path('../../../spec_helper', __FILE__) +require File.expand_path('../fixtures/classes', __FILE__) + +# erf method is the "error function" encountered in integrating the normal +# distribution (which is a normalized form of the Gaussian function). +describe "Math.erf" do + it "returns a float" do + Math.erf(1).should be_kind_of(Float) + end + + it "returns the error function of the argument" do + Math.erf(0).should be_close(0.0, TOLERANCE) + Math.erf(1).should be_close(0.842700792949715, TOLERANCE) + Math.erf(-1).should be_close(-0.842700792949715, TOLERANCE) + Math.erf(0.5).should be_close(0.520499877813047, TOLERANCE) + Math.erf(-0.5).should be_close(-0.520499877813047, TOLERANCE) + Math.erf(10000).should be_close(1.0, TOLERANCE) + Math.erf(-10000).should be_close(-1.0, TOLERANCE) + Math.erf(0.00000000000001).should be_close(0.0, TOLERANCE) + Math.erf(-0.00000000000001).should be_close(0.0, TOLERANCE) + end + + it "raises a TypeError if the argument cannot be coerced with Float()" do + lambda { Math.erf("test") }.should raise_error(TypeError) + end + + it "returns NaN given NaN" do + Math.erf(nan_value).nan?.should be_true + end + + it "raises a TypeError if the argument is nil" do + lambda { Math.erf(nil) }.should raise_error(TypeError) + end + + it "accepts any argument that can be coerced with Float()" do + Math.erf(MathSpecs::Float.new).should be_close(0.842700792949715, TOLERANCE) + end +end + +describe "Math#erf" do + it "is accessible as a private instance method" do + IncludesMath.new.send(:erf, 3.1415).should be_close(0.999991118444483, TOLERANCE) + end +end |