1DLAGS2(1)           LAPACK auxiliary routine (version 3.2)           DLAGS2(1)
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NAME

6       DLAGS2 - computes 2-by-2 orthogonal matrices U, V and Q, such that if (
7       UPPER ) then   U'*A*Q = U'*( A1 A2 )*Q = ( x 0 )  ( 0 A3 ) ( x x )  and
8       V'*B*Q = V'*( B1 B2 )*Q = ( x 0 )  ( 0 B3 ) ( x x )  or if ( .NOT.UPPER
9       ) then   U'*A*Q = U'*( A1 0 )*Q = ( x x )  ( A2  A3  )  (  0  x  )  and
10       V'*B*Q  =  V'*(  B1 0 )*Q = ( x x )  ( B2 B3 ) ( 0 x )  The rows of the
11       transformed A and B are parallel, where   U = ( CSU SNU ), V  =  (  CSV
12       SNV  ),  Q  =  (  CSQ SNQ )  ( -SNU CSU ) ( -SNV CSV ) ( -SNQ CSQ )  Z'
13       denotes the transpose of Z
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SYNOPSIS

16       SUBROUTINE DLAGS2( UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU,  CSV,  SNV,
17                          CSQ, SNQ )
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19           LOGICAL        UPPER
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21           DOUBLE         PRECISION  A1,  A2,  A3,  B1, B2, B3, CSQ, CSU, CSV,
22                          SNQ, SNU, SNV
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PURPOSE

25       DLAGS2 computes 2-by-2 orthogonal matrices U, V and Q, such that  if  (
26       UPPER ) then
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ARGUMENTS

29       UPPER   (input) LOGICAL
30               = .TRUE.: the input matrices A and B are upper triangular.
31               = .FALSE.: the input matrices A and B are lower triangular.
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33       A1      (input) DOUBLE PRECISION
34               A2       (input) DOUBLE PRECISION A3      (input) DOUBLE PRECI‐
35               SION On entry, A1, A2 and A3 are elements of the  input  2-by-2
36               upper (lower) triangular matrix A.
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38       B1      (input) DOUBLE PRECISION
39               B2       (input) DOUBLE PRECISION B3      (input) DOUBLE PRECI‐
40               SION On entry, B1, B2 and B3 are elements of the  input  2-by-2
41               upper (lower) triangular matrix B.
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43       CSU     (output) DOUBLE PRECISION
44               SNU     (output) DOUBLE PRECISION The desired orthogonal matrix
45               U.
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47       CSV     (output) DOUBLE PRECISION
48               SNV     (output) DOUBLE PRECISION The desired orthogonal matrix
49               V.
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51       CSQ     (output) DOUBLE PRECISION
52               SNQ     (output) DOUBLE PRECISION The desired orthogonal matrix
53               Q.
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57 LAPACK auxiliary routine (versionNo3v.e2m)ber 2008                       DLAGS2(1)
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