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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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slanv2(l) |
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SLANV2 - compute the Schur factorization of a real 2-by-2 nonsymmetric matrix in standard form
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SUBROUTINE SLANV2( |
A, B, C, D, RT1R, RT1I, RT2R, RT2I, CS, SN ) | ||
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REAL |
A, B, C, CS, D, RT1I, RT1R, RT2I, RT2R, SN |
SLANV2 computes
the Schur factorization of a real 2-by-2 nonsymmetric matrix
in standard form:
[ A B ] = [ CS -SN ] [ AA BB ] [ CS SN ]
[ C D ] [ SN CS ] [ CC DD ] [-SN CS ]
where either
1) CC = 0 so that AA and DD are real eigenvalues of the
matrix, or 2) AA = DD and BB*CC < 0, so that AA + or -
sqrt(BB*CC) are complex conjugate eigenvalues.
A (input/output) REAL
B (input/output) REAL C (input/output) REAL D (input/output) REAL On entry, the elements of the input matrix. On exit, they are overwritten by the elements of the standardised Schur form.
RT1R (output) REAL
RT1I (output) REAL RT2R (output) REAL RT2I (output) REAL The real and imaginary parts of the eigenvalues. If the eigenvalues are a complex conjugate pair, RT1I > 0.
CS (output) REAL
SN (output) REAL Parameters of the rotation matrix.
Modified by V.
Sima, Research Institute for Informatics, Bucharest,
Romania, to reduce the risk of cancellation errors,
when computing real eigenvalues, and to ensure, if possible,
that abs(RT1R) >= abs(RT2R).
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slanv2(l) | |