# dlags2.f(3) [centos man page]

dlags2.f(3) LAPACK dlags2.f(3)NAME

dlags2.f-SYNOPSIS

Functions/Subroutines subroutine dlags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ) DLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B such that the rows of the transformed A and B are parallel.Function/Subroutine Documentation subroutine dlags2 (logicalUPPER, double precisionA1, double precisionA2, double precisionA3, double precisionB1, double precisionB2, double precisionB3, double precisionCSU, double precisionSNU, double precisionCSV, double precisionSNV, double precisionCSQ, double precisionSNQ) DLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B such that the rows of the transformed A and B are parallel. Purpose: 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 ) (CSU ) (-SNUCSV ) (-SNVCSQ ) Z**T denotes the transpose of Z. 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. A1 A1 is DOUBLE PRECISION A2 A2 is DOUBLE PRECISION A3 A3 is DOUBLE PRECISION On entry, A1, A2 and A3 are elements of the input 2-by-2 upper (lower) triangular matrix A. B1 B1 is DOUBLE PRECISION B2 B2 is DOUBLE PRECISION B3 B3 is DOUBLE PRECISION On entry, B1, B2 and B3 are elements of the input 2-by-2 upper (lower) triangular matrix B. CSU CSU is DOUBLE PRECISION SNU SNU is DOUBLE PRECISION The desired orthogonal matrix U. CSV CSV is DOUBLE PRECISION SNV SNV is DOUBLE PRECISION The desired orthogonal matrix V. CSQ CSQ is DOUBLE PRECISION SNQ SNQ is DOUBLE PRECISION The desired orthogonal matrix Q. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 Definition at line 152 of file dlags2.f.-SNQAuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 dlags2.f(3)

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zlags2.f(3) LAPACK zlags2.f(3)NAME

zlags2.f-SYNOPSIS

Functions/Subroutines subroutine zlags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ) ZLAGS2Function/Subroutine Documentation 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 Purpose: 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 ) 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. 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. A1 A1 is DOUBLE PRECISION A2 A2 is COMPLEX*16 A3 A3 is DOUBLE PRECISION On entry, A1, A2 and A3 are elements of the input 2-by-2 upper (lower) triangular matrix A. B1 B1 is DOUBLE PRECISION B2 B2 is COMPLEX*16 B3 B3 is DOUBLE PRECISION On entry, B1, B2 and B3 are elements of the input 2-by-2 upper (lower) triangular matrix B. CSU CSU is DOUBLE PRECISION SNU SNU is COMPLEX*16 The desired unitary matrix U. CSV CSV is DOUBLE PRECISION SNV SNV is COMPLEX*16 The desired unitary matrix V. CSQ CSQ is DOUBLE PRECISION SNQ SNQ is COMPLEX*16 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 zlags2.f.AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 zlags2.f(3)