/**
* Compute the eigenvalue of square matrix.
*
* @param matrix Input matrix A.
* @return A pair of column vectors A and B s.t. each row of A + Bi is a eigenvalue of the
* underlying matrix
* @throws UnsupportedOperationException if unable to compute
*/
public Pair compute(Matrix matrix) {
Throw.when()
.isNull(() -> matrix, () -> "No input matrix.")
.isFalse(
() -> matrix.getRowCount() == matrix.getColCount(),
() -> "Input matrix is not square.");
switch (matrix.getRowCount()) {
case 0:
return Pair.EMPTY;
case 1:
return Pair.of(Matrices.scalar(matrix.get(0, 0)), Matrices.zeros(1));
case 2:
return DoubleShift.of(matrix, 0).eig();
default:
break;
}
return this.findEig(this.qrImpl.compute(new DefaultMatrix(matrix), null, false));
}
