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51 lines
1.6 KiB
Ruby
51 lines
1.6 KiB
Ruby
require_relative '../../spec_helper'
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require_relative 'fixtures/classes'
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require 'matrix'
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describe "Matrix#**" do
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describe "given an integer _n_" do
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it "multiples the Matrix by itself _n_ times" do
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m = Matrix[ [7,6], [3,9] ]
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(m ** 1).should == m
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(m ** 2).should == Matrix[ [67, 96], [48,99] ]
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(m ** 2).should == m * m
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(m ** 3).should == m * m * m
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(m ** 4).should == m * m * m * m
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(m ** 5).should == m * m * m * m * m
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end
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it "raises a ErrDimensionMismatch for non square matrices" do
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m = Matrix[ [1, 1], [1, 2], [2, 3]]
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-> { m ** 3 }.should raise_error(Matrix::ErrDimensionMismatch)
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-> { m ** 0 }.should raise_error(Matrix::ErrDimensionMismatch)
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end
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describe "that is <= 0" do
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it "returns the inverse of **(-n)" do
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m = Matrix[ [1, 1], [1, 2] ]
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(m ** -2).should == Matrix[ [5, -3], [-3, 2]]
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(m ** -4).should == (m.inverse ** 4)
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end
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it "raises a ErrDimensionMismatch for irregular matrices" do
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m = Matrix[ [1, 1], [1, 1] ]
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-> { m ** -2 }.should raise_error(Matrix::ErrNotRegular)
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-> { m ** 0 }.should raise_error(Matrix::ErrNotRegular)
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end
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end
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end
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it "returns the power for non integer powers" do
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a = Matrix[[5, 4], [4, 5]]
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((a ** 0.5) ** 2).round(8).should == a
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a = Matrix[[7, 10], [15, 22]]
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((a ** 0.25) ** 4).round(8).should == a
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end
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describe "for a subclass of Matrix" do
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it "returns an instance of that subclass" do
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(MatrixSub.ins ** 1).should be_an_instance_of(MatrixSub)
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end
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end
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end
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