require_relative '../../spec_helper' require_relative 'fixtures/classes' 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 infinity 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