LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  zlags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ) 
ZLAGS2 
subroutine zlags2  (  logical  UPPER, 
double precision  A1,  
complex*16  A2,  
double precision  A3,  
double precision  B1,  
complex*16  B2,  
double precision  B3,  
double precision  CSU,  
complex*16  SNU,  
double precision  CSV,  
complex*16  SNV,  
double precision  CSQ,  
complex*16  SNQ  
) 
ZLAGS2
Download ZLAGS2 + dependencies [TGZ] [ZIP] [TXT]ZLAGS2 computes 2by2 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 ) and 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 ) and V**H *B*Q = V**H *( B1 0 )*Q = ( x x ) ( B2 B3 ) ( 0 x ) where 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 2by2 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 zero.
[in]  UPPER  UPPER is LOGICAL = .TRUE.: the input matrices A and B are upper triangular. = .FALSE.: the input matrices A and B are lower triangular. 
[in]  A1  A1 is DOUBLE PRECISION 
[in]  A2  A2 is COMPLEX*16 
[in]  A3  A3 is DOUBLE PRECISION On entry, A1, A2 and A3 are elements of the input 2by2 upper (lower) triangular matrix A. 
[in]  B1  B1 is DOUBLE PRECISION 
[in]  B2  B2 is COMPLEX*16 
[in]  B3  B3 is DOUBLE PRECISION On entry, B1, B2 and B3 are elements of the input 2by2 upper (lower) triangular matrix B. 
[out]  CSU  CSU is DOUBLE PRECISION 
[out]  SNU  SNU is COMPLEX*16 The desired unitary matrix U. 
[out]  CSV  CSV is DOUBLE PRECISION 
[out]  SNV  SNV is COMPLEX*16 The desired unitary matrix V. 
[out]  CSQ  CSQ is DOUBLE PRECISION 
[out]  SNQ  SNQ is COMPLEX*16 The desired unitary matrix Q. 
Definition at line 158 of file zlags2.f.