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require_relative '../../spec_helper'
require_relative 'fixtures/classes'
require 'matrix'
describe "Matrix#**" do
describe "given an integer _n_" do
it "multiples the Matrix by itself _n_ times" do
m = Matrix[ [7,6], [3,9] ]
(m ** 1).should == m
(m ** 2).should == Matrix[ [67, 96], [48,99] ]
(m ** 2).should == m * m
(m ** 3).should == m * m * m
(m ** 4).should == m * m * m * m
(m ** 5).should == m * m * m * m * m
end
it "raises a ErrDimensionMismatch for non square matrices" do
m = Matrix[ [1, 1], [1, 2], [2, 3]]
-> { m ** 3 }.should raise_error(Matrix::ErrDimensionMismatch)
-> { m ** 0 }.should raise_error(Matrix::ErrDimensionMismatch)
end
describe "that is < 0" do
it "returns the inverse of **(-n)" do
m = Matrix[ [1, 1], [1, 2] ]
(m ** -2).should == Matrix[ [5, -3], [-3, 2]]
(m ** -4).should == (m.inverse ** 4)
end
it "raises a ErrNotRegular for irregular matrices" do
m = Matrix[ [1, 1], [1, 1] ]
-> { m ** -2 }.should raise_error(Matrix::ErrNotRegular)
end
end
ruby_version_is '3.1.0' do # https://bugs.ruby-lang.org/issues/17521
describe "that is 0" do
it "returns the identity for square matrices" do
m = Matrix[ [1, 1], [1, 1] ]
(m ** 0).should == Matrix.identity(2)
end
it "raises an ErrDimensionMismatch for non-square matrices" do
m = Matrix[ [1, 1] ]
-> { m ** 0 }.should raise_error(Matrix::ErrDimensionMismatch)
end
end
end
end
it "returns the power for non integer powers" do
a = Matrix[[5, 4], [4, 5]]
((a ** 0.5) ** 2).round(8).should == a
a = Matrix[[7, 10], [15, 22]]
((a ** 0.25) ** 4).round(8).should == a
end
describe "for a subclass of Matrix" do
it "returns an instance of that subclass" do
(MatrixSub.ins ** 1).should be_an_instance_of(MatrixSub)
end
end
end
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