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# srps/polynomial.rbSecret Created Dec 11, 2009

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RPCFN #4 entry
 # I've attached the tests to the bottom of this class also, might come in handy class Polynomial def initialize(poly) coef, @result= poly.length, "" # let's create some vars we'll need raise ArgumentError, "Need at least 2 coefficients" if coef < 2 # if you try to make a monomial...boom! poly.each do |item| # let's treat the array with a nice block encasing coef -= 1 @result << ("#{'+' unless item < 1 || @result == ""}" << # puts '+' when number isn't negative or leading "#{item == -1 ? "-" : "" }#{item.to_s if item.abs > 1}" << # negatives already come with sign (item.zero? ? "" : "#{case coef when 1 then "x" when 0 then "" else "x^" end}" << # eliminate zero coeffs' x, zero multipliers, write only needed stuff "#{coef.to_s unless coef < 2}")) # puts the coefficient when applicable (above 1) end @result = "0" if @result.eql? "" # Could've been done in the poly block, but it's cleaner & faster this way end def to_s @result # result already comes nicely formatted in a string, let's display it end end require 'test/unit' require 'test/unit/ui/console/testrunner' require 'polynomial' class Polynomial_Test < Test::Unit::TestCase def setup @p1 = Polynomial.new([-3,-4,1,0,6]) @p2 = Polynomial.new([1,0,2]) @p3 = Polynomial.new([-1,-2,3,0]) @p4 = Polynomial.new([0,0,0]) @p5 = Polynomial.new([-1,0,12,0,-2,0,0,1,-9]) @p6 = Polynomial.new([0,0,1,5,6]) @p7 = Polynomial.new([-4.1,0,-5.45]) end def test_first_negative assert_equal("-3x^4-4x^3+x^2+6", @p1.to_s) end def test_simple assert_equal("x^2+2", @p2.to_s) end def test_first_minus_one assert_equal("-x^3-2x^2+3x", @p3.to_s) end def test_all_zero assert_equal("0", @p4.to_s) end def test_lots_of_zeros assert_equal("-x^8+12x^6-2x^4+x-9", @p5.to_s) end def test_leading_zeros assert_equal("x^2+5x+6", @p6.to_s) end def test_non_integers assert_equal("-4.1x^2-5.45", @p7.to_s) end def test_error_coef_number e = assert_raise(ArgumentError) { Polynomial.new([1]) } assert_match(/Need at least 2 coefficients/, e.message) end end Test::Unit::UI::Console::TestRunner.run(Polynomial_Test)