diff options
| -rw-r--r-- | lib/matrix.rb | 12 | ||||
| -rw-r--r-- | spec/ruby/library/matrix/antisymmetric_spec.rb | 35 |
2 files changed, 47 insertions, 0 deletions
diff --git a/lib/matrix.rb b/lib/matrix.rb index 923e716b35..4a61976b0e 100644 --- a/lib/matrix.rb +++ b/lib/matrix.rb @@ -802,6 +802,18 @@ class Matrix end # + # Returns +true+ if this is an antisymmetric matrix. + # Raises an error if matrix is not square. + # + def antisymmetric? + Matrix.Raise ErrDimensionMismatch unless square? + each_with_index(:upper) do |e, row, col| + return false unless e == -rows[col][row] + end + true + end + + # # Returns +true+ if this is a unitary matrix # Raises an error if matrix is not square. # diff --git a/spec/ruby/library/matrix/antisymmetric_spec.rb b/spec/ruby/library/matrix/antisymmetric_spec.rb new file mode 100644 index 0000000000..e5b2d51758 --- /dev/null +++ b/spec/ruby/library/matrix/antisymmetric_spec.rb @@ -0,0 +1,35 @@ +require File.expand_path('../../../spec_helper', __FILE__) +require 'matrix' + +describe "Matrix#antisymmetric?" do + it "returns true for an antisymmetric Matrix" do + Matrix[[0, -2, Complex(1, 3)], [2, 0, 5], [-Complex(1, 3), -5, 0]].antisymmetric?.should be_true + end + + it "returns true for a 0x0 empty matrix" do + Matrix.empty.antisymmetric?.should be_true + end + + it "returns false for non-antisymmetric matrices" do + [ + Matrix[[1, 2, 3], [4, 5, 6], [7, 8, 9]], + Matrix[[1, -2, 3], [2, 0, 6], [-3, -6, 0]], # wrong diagonal element + Matrix[[0, 2, -3], [2, 0, 6], [-3, 6, 0]] # only signs wrong + ].each do |matrix| + matrix.antisymmetric?.should be_false + end + end + + it "raises an error for rectangular matrices" do + [ + Matrix[[0], [0]], + Matrix[[0, 0]], + Matrix.empty(0, 2), + Matrix.empty(2, 0), + ].each do |rectangular_matrix| + lambda { + rectangular_matrix.antisymmetric? + }.should raise_error(Matrix::ErrDimensionMismatch) + end + end +end |