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Singular
linearAlgebra_ip.h
Go to the documentation of this file.
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#ifndef LINEARALGEBRA_H
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#define LINEARALGEBRA_H
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#include "
Singular/lists.h
"
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#include "
kernel/linear_algebra/linearAlgebra.h
"
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/**
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* Computes all eigenvalues of a given real quadratic matrix with
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* multiplicites.
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*
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* The method assumes that the current ground field is the complex numbers.
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* Computations are based on the QR double shift algorithm involving
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* Hessenberg form and householder transformations.
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* If the algorithm works, then it returns a list with two entries which
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* are again lists of the same size:
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* _[1][i] is the i-th mutually distinct eigenvalue that was found,
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* _[2][i] is the (int) multiplicity of _[1][i].
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* If the algorithm does not work (due to an ill-posed matrix), a list with
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* the single entry (int)0 is returned.
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* 'tol1' is used for detection of deflation in the actual qr double shift
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* algorithm.
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* 'tol2' is used for ending Heron's iteration whenever square roots
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* are being computed.
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* 'tol3' is used to distinguish between distinct eigenvalues: When
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* the Euclidean distance between two computed eigenvalues is less then
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* tol3, then they will be regarded equal, resulting in a higher
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* multiplicity of the corresponding eigenvalue.
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*
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* @return a list with one entry (int)0, or two entries which are again lists
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**/
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lists
qrDoubleShift
(
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const
matrix
A
,
/**< [in] the quadratic matrix */
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const
number tol1,
/**< [in] tolerance for deflation */
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const
number tol2,
/**< [in] tolerance for square roots */
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const
number tol3,
/**< [in] tolerance for distinguishing
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eigenvalues */
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const
ring r=
currRing
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);
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#endif
ip_smatrix
Definition:
matpol.h:15
slists
Definition:
lists.h:24
linearAlgebra.h
qrDoubleShift
lists qrDoubleShift(const matrix A, const number tol1, const number tol2, const number tol3, const ring r=currRing)
Computes all eigenvalues of a given real quadratic matrix with multiplicites.
Definition:
linearAlgebra_ip.cc:41
lists.h
currRing
VAR ring currRing
Widely used global variable which specifies the current polynomial ring for Singular interpreter and ...
Definition:
polys.cc:13
A
#define A
Definition:
sirandom.c:24
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