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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine clags2 | ( | logical | UPPER, |
real | A1, | ||
complex | A2, | ||
real | A3, | ||
real | B1, | ||
complex | B2, | ||
real | B3, | ||
real | CSU, | ||
complex | SNU, | ||
real | CSV, | ||
complex | SNV, | ||
real | CSQ, | ||
complex | SNQ | ||
) |
CLAGS2
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CLAGS2 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 ) 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 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 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 REAL |
[in] | A2 | A2 is COMPLEX |
[in] | A3 | A3 is REAL On entry, A1, A2 and A3 are elements of the input 2-by-2 upper (lower) triangular matrix A. |
[in] | B1 | B1 is REAL |
[in] | B2 | B2 is COMPLEX |
[in] | B3 | B3 is REAL On entry, B1, B2 and B3 are elements of the input 2-by-2 upper (lower) triangular matrix B. |
[out] | CSU | CSU is REAL |
[out] | SNU | SNU is COMPLEX The desired unitary matrix U. |
[out] | CSV | CSV is REAL |
[out] | SNV | SNV is COMPLEX The desired unitary matrix V. |
[out] | CSQ | CSQ is REAL |
[out] | SNQ | SNQ is COMPLEX The desired unitary matrix Q. |
Definition at line 160 of file clags2.f.