DLANV2 computes the Schur factorization of a real 2-by-2 nonsymmetric matrix in standard form.
DLANV2 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 is DOUBLE PRECISION
B is DOUBLE PRECISION
C is DOUBLE PRECISION
D is DOUBLE PRECISION On entry, the elements of the input matrix. On exit, they are overwritten by the elements of the standardised Schur form.
RT1R is DOUBLE PRECISION
RT1I is DOUBLE PRECISION
RT2R is DOUBLE PRECISION
RT2I is DOUBLE PRECISION The real and imaginary parts of the eigenvalues. If the eigenvalues are a complex conjugate pair, RT1I > 0.
CS is DOUBLE PRECISION
SN is DOUBLE PRECISION Parameters of the rotation matrix.
Univ. of California Berkeley
Univ. of Colorado Denver
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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