zlags2.f(3) LAPACK zlags2.f(3)
subroutine zlags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ)
subroutine zlags2 (logicalUPPER, double precisionA1, complex*16A2, double precisionA3, double
precisionB1, complex*16B2, double precisionB3, double precisionCSU, complex*16SNU, double
precisionCSV, complex*16SNV, double precisionCSQ, complex*16SNQ)
ZLAGS2 computes 2-by-2 unitary matrices U, V and Q, such
that if ( UPPER ) then
U**H *A*Q = U**H *( A1 A2 )*Q = ( x 0 )
( 0 A3 ) ( x x )
V**H*B*Q = V**H *( B1 B2 )*Q = ( x 0 )
( 0 B3 ) ( x x )
or if ( .NOT.UPPER ) then
U**H *A*Q = U**H *( A1 0 )*Q = ( x x )
( A2 A3 ) ( 0 x )
V**H *B*Q = V**H *( B1 0 )*Q = ( x x )
( B2 B3 ) ( 0 x )
U = ( CSU SNU ), V = ( CSV SNV ),
( -SNU**H CSU ) ( -SNV**H CSV )
Q = ( CSQ SNQ )
( -SNQ**H CSQ )
The rows of the transformed A and B are parallel. Moreover, if the
input 2-by-2 matrix A is not zero, then the transformed (1,1) entry
of A is not zero. If the input matrices A and B are both not zero,
then the transformed (2,2) element of B is not zero, except when the
first rows of input A and B are parallel and the second rows are
UPPER is LOGICAL
= .TRUE.: the input matrices A and B are upper triangular.
= .FALSE.: the input matrices A and B are lower triangular.
A1 is DOUBLE PRECISION
A2 is COMPLEX*16
A3 is DOUBLE PRECISION
On entry, A1, A2 and A3 are elements of the input 2-by-2
upper (lower) triangular matrix A.
B1 is DOUBLE PRECISION
B2 is COMPLEX*16
B3 is DOUBLE PRECISION
On entry, B1, B2 and B3 are elements of the input 2-by-2
upper (lower) triangular matrix B.
CSU is DOUBLE PRECISION
SNU is COMPLEX*16
The desired unitary matrix U.
CSV is DOUBLE PRECISION
SNV is COMPLEX*16
The desired unitary matrix V.
CSQ is DOUBLE PRECISION
SNQ is COMPLEX*16
The desired unitary matrix Q.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
Definition at line 158 of file zlags2.f.
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 zlags2.f(3)