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require 'bigdecimal'
describe :bigdecimal_power, shared: true do
it "powers of self" do
e3_minus = BigDecimal("3E-20001")
e3_minus_power_2 = BigDecimal("9E-40002")
e3_plus = BigDecimal("3E20001")
e2_plus = BigDecimal("2E40001")
e5_minus = BigDecimal("5E-40002")
e = BigDecimal("1.00000000000000000000123456789")
one = BigDecimal("1")
ten = BigDecimal("10")
# The tolerance is dependent upon the size of BASE_FIG
tolerance = BigDecimal("1E-70")
ten_powers = BigDecimal("1E10000")
pi = BigDecimal("3.14159265358979")
e3_minus.send(@method, 2).should == e3_minus_power_2
e3_plus.send(@method, 0).should == 1
e3_minus.send(@method, 1).should == e3_minus
e2_plus.send(@method, -1).should == e5_minus
e2_plus.send(@method, -1).should == e5_minus.power(1)
(e2_plus.send(@method, -1) * e5_minus.send(@method, -1)).should == 1
e.send(@method, 2).should == e * e
e.send(@method, -1).should be_close(one.div(e, 120), tolerance)
ten.send(@method, 10000).should == ten_powers
pi.send(@method, 10).should be_close(Math::PI ** 10, TOLERANCE)
end
it "powers of 1 equal 1" do
one = BigDecimal("1")
one.send(@method, 0).should == 1
one.send(@method, 1).should == 1
one.send(@method, 10).should == 1
one.send(@method, -10).should == 1
end
it "0 to power of 0 is 1" do
zero = BigDecimal("0")
zero.send(@method, 0).should == 1
end
it "0 to powers < 0 is Infinity" do
zero = BigDecimal("0")
infinity = BigDecimal("Infinity")
zero.send(@method, -10).should == infinity
zero.send(@method, -1).should == infinity
end
it "other powers of 0 are 0" do
zero = BigDecimal("0")
zero.send(@method, 1).should == 0
zero.send(@method, 10).should == 0
end
it "returns NaN if self is NaN" do
BigDecimal("NaN").send(@method, -5).nan?.should == true
BigDecimal("NaN").send(@method, 5).nan?.should == true
end
it "returns 0.0 if self is infinite and argument is negative" do
BigDecimal("Infinity").send(@method, -5).should == 0
BigDecimal("-Infinity").send(@method, -5).should == 0
end
it "returns infinite if self is infinite and argument is positive" do
infinity = BigDecimal("Infinity")
BigDecimal("Infinity").send(@method, 4).should == infinity
BigDecimal("-Infinity").send(@method, 4).should == infinity
BigDecimal("Infinity").send(@method, 5).should == infinity
BigDecimal("-Infinity").send(@method, 5).should == -infinity
end
end
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