LAPACK  3.4.2 LAPACK: Linear Algebra PACKage
slags2.f File Reference

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## Functions/Subroutines

subroutine slags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ)
SLAGS2 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 slags2 ( logical UPPER, real A1, real A2, real A3, real B1, real B2, real B3, real CSU, real SNU, real CSV, real SNV, real CSQ, real SNQ )

SLAGS2 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:
SLAGS2 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.
Parameters:
 [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 REAL [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 REAL [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 REAL The desired orthogonal matrix U. [out] CSV CSV is REAL [out] SNV SNV is REAL The desired orthogonal matrix V. [out] CSQ CSQ is REAL [out] SNQ SNQ is REAL The desired orthogonal matrix Q.
Date:
September 2012

Definition at line 152 of file slags2.f.

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