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require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)
require 'bigdecimal'
describe "BigDecimal#sqrt" do
before :each do
@one = BigDecimal("1")
@zero = BigDecimal("0")
@zero_pos = BigDecimal("+0")
@zero_neg = BigDecimal("-0")
@two = BigDecimal("2.0")
@three = BigDecimal("3.0")
@nan = BigDecimal("NaN")
@infinity = BigDecimal("Infinity")
@infinity_minus = BigDecimal("-Infinity")
@one_minus = BigDecimal("-1")
@frac_1 = BigDecimal("1E-99999")
@frac_2 = BigDecimal("0.9E-99999")
end
it "returns square root of 2 with desired precision" do
string = "1.41421356237309504880168872420969807856967187537694807317667973799073247846210703885038753432764157"
(1..99).each { |idx|
@two.sqrt(idx).should be_close(BigDecimal(string), BigDecimal("1E-#{idx-1}"))
}
end
it "returns square root of 3 with desired precision" do
sqrt_3 = "1.732050807568877293527446341505872366942805253810380628055806979451933016908800037081146186757248575"
(1..99).each { |idx|
@three.sqrt(idx).should be_close(BigDecimal(sqrt_3), BigDecimal("1E-#{idx-1}"))
}
end
it "returns square root of 121 with desired precision" do
BigDecimal('121').sqrt(5).should be_close(11, 0.00001)
end
it "returns square root of 0.9E-99999 with desired precision" do
@frac_2.sqrt(1).to_s.should =~ /\A0\.3E-49999\z/i
end
it "raises ArgumentError when no argument is given" do
lambda {
@one.sqrt
}.should raise_error(ArgumentError)
end
it "raises ArgumentError if a negative number is given" do
lambda {
@one.sqrt(-1)
}.should raise_error(ArgumentError)
end
it "raises ArgumentError if 2 arguments are given" do
lambda {
@one.sqrt(1, 1)
}.should raise_error(ArgumentError)
end
it "raises TypeError if nil is given" do
lambda {
@one.sqrt(nil)
}.should raise_error(TypeError)
end
it "raises TypeError if a string is given" do
lambda {
@one.sqrt("stuff")
}.should raise_error(TypeError)
end
it "raises TypeError if a plain Object is given" do
lambda {
@one.sqrt(Object.new)
}.should raise_error(TypeError)
end
it "returns 1 if precision is 0 or 1" do
@one.sqrt(1).should == 1
@one.sqrt(0).should == 1
end
it "raises FloatDomainError on negative values" do
lambda {
BigDecimal('-1').sqrt(10)
}.should raise_error(FloatDomainError)
end
it "returns positive infitinity for infinity" do
@infinity.sqrt(1).should == @infinity
end
it "raises FloatDomainError for negative infinity" do
lambda {
@infinity_minus.sqrt(1)
}.should raise_error(FloatDomainError)
end
it "raises FloatDomainError for NaN" do
lambda {
@nan.sqrt(1)
}.should raise_error(FloatDomainError)
end
it "returns 0 for 0, +0.0 and -0.0" do
@zero.sqrt(1).should == 0
@zero_pos.sqrt(1).should == 0
@zero_neg.sqrt(1).should == 0
end
end
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