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LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
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Go to the source code of this file.
Functions/Subroutines | |
subroutine | DLAGS2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ) |
DLAGS2 |
subroutine DLAGS2 | ( | LOGICAL | UPPER, |
DOUBLE PRECISION | A1, | ||
DOUBLE PRECISION | A2, | ||
DOUBLE PRECISION | A3, | ||
DOUBLE PRECISION | B1, | ||
DOUBLE PRECISION | B2, | ||
DOUBLE PRECISION | B3, | ||
DOUBLE PRECISION | CSU, | ||
DOUBLE PRECISION | SNU, | ||
DOUBLE PRECISION | CSV, | ||
DOUBLE PRECISION | SNV, | ||
DOUBLE PRECISION | CSQ, | ||
DOUBLE PRECISION | SNQ | ||
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DLAGS2
Download DLAGS2 + dependencies [TGZ] [ZIP] [TXT]DLAGS2 computes 2-by-2 orthogonal matrices U, V and Q, such that if ( UPPER ) then U**T *A*Q = U**T *( A1 A2 )*Q = ( x 0 ) ( 0 A3 ) ( x x ) and V**T*B*Q = V**T *( B1 B2 )*Q = ( x 0 ) ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then U**T *A*Q = U**T *( A1 0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and V**T*B*Q = V**T*( B1 0 )*Q = ( x x ) ( B2 B3 ) ( 0 x ) The rows of the transformed A and B are parallel, where U = ( CSU SNU ), V = ( CSV SNV ), Q = ( CSQ SNQ ) ( -SNU CSU ) ( -SNV CSV ) ( -SNQ CSQ ) Z**T denotes the transpose of Z.
[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 DOUBLE PRECISION |
[in] | A3 | A3 is DOUBLE PRECISION On entry, A1, A2 and A3 are elements of the input 2-by-2 upper (lower) triangular matrix A. |
[in] | B1 | B1 is DOUBLE PRECISION |
[in] | B2 | B2 is DOUBLE PRECISION |
[in] | B3 | B3 is DOUBLE PRECISION On entry, B1, B2 and B3 are elements of the input 2-by-2 upper (lower) triangular matrix B. |
[out] | CSU | CSU is DOUBLE PRECISION |
[out] | SNU | SNU is DOUBLE PRECISION The desired orthogonal matrix U. |
[out] | CSV | CSV is DOUBLE PRECISION |
[out] | SNV | SNV is DOUBLE PRECISION The desired orthogonal matrix V. |
[out] | CSQ | CSQ is DOUBLE PRECISION |
[out] | SNQ | SNQ is DOUBLE PRECISION The desired orthogonal matrix Q. |
Definition at line 152 of file dlags2.f.