clags2.f (3)  Linux Manuals
NAME
clags2.f 
SYNOPSIS
Functions/Subroutines
subroutine clags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ)
CLAGS2
Function/Subroutine Documentation
subroutine clags2 (logicalUPPER, realA1, complexA2, realA3, realB1, complexB2, realB3, realCSU, complexSNU, realCSV, complexSNV, realCSQ, complexSNQ)
CLAGS2
Purpose:

CLAGS2 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.
Parameters:

UPPER
UPPER is LOGICAL = .TRUE.: the input matrices A and B are upper triangular. = .FALSE.: the input matrices A and B are lower triangular.
A1A1 is REAL
A2A2 is COMPLEX
A3A3 is REAL On entry, A1, A2 and A3 are elements of the input 2by2 upper (lower) triangular matrix A.
B1B1 is REAL
B2B2 is COMPLEX
B3B3 is REAL On entry, B1, B2 and B3 are elements of the input 2by2 upper (lower) triangular matrix B.
CSUCSU is REAL
SNUSNU is COMPLEX The desired unitary matrix U.
CSVCSV is REAL
SNVSNV is COMPLEX The desired unitary matrix V.
CSQCSQ is REAL
SNQSNQ is COMPLEX The desired unitary matrix Q.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 November 2011
Definition at line 158 of file clags2.f.
Author
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