slags2 (l)  Linux Manuals
slags2: computes 2by2 orthogonal matrices U, V and Q, such that if ( UPPER ) then Uaq*A*Q = Uaq*( A1 A2 )*Q = ( x 0 ) ( 0 A3 ) ( x x ) and Vaq*B*Q = Vaq*( B1 B2 )*Q = ( x 0 ) ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then Uaq*A*Q = Uaq*( A1 0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and Vaq*B*Q = Vaq*( 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 ) Zaq denotes the transpose of Z
Command to display slags2
manual in Linux: $ man l slags2
NAME
SLAGS2  computes 2by2 orthogonal matrices U, V and Q, such that if ( UPPER ) then Uaq*A*Q = Uaq*( A1 A2 )*Q = ( x 0 ) ( 0 A3 ) ( x x ) and Vaq*B*Q = Vaq*( B1 B2 )*Q = ( x 0 ) ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then Uaq*A*Q = Uaq*( A1 0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and Vaq*B*Q = Vaq*( 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 ) Zaq denotes the transpose of Z
SYNOPSIS
 SUBROUTINE SLAGS2(

UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV,
SNV, CSQ, SNQ )

LOGICAL
UPPER

REAL
A1, A2, A3, B1, B2, B3, CSQ, CSU, CSV, SNQ,
SNU, SNV
PURPOSE
SLAGS2 computes 2by2 orthogonal matrices U, V and Q, such
that if ( UPPER ) then
ARGUMENTS
 UPPER (input) LOGICAL

= .TRUE.: the input matrices A and B are upper triangular.
= .FALSE.: the input matrices A and B are lower triangular.
 A1 (input) REAL

A2 (input) REAL
A3 (input) REAL
On entry, A1, A2 and A3 are elements of the input 2by2
upper (lower) triangular matrix A.
 B1 (input) REAL

B2 (input) REAL
B3 (input) REAL
On entry, B1, B2 and B3 are elements of the input 2by2
upper (lower) triangular matrix B.
 CSU (output) REAL

SNU (output) REAL
The desired orthogonal matrix U.
 CSV (output) REAL

SNV (output) REAL
The desired orthogonal matrix V.
 CSQ (output) REAL

SNQ (output) REAL
The desired orthogonal matrix Q.
Pages related to slags2
 slags2 (3)
 slag2 (l)  computes the eigenvalues of a 2 x 2 generalized eigenvalue problem A  w B, with scaling as necessary to avoid over/underflow
 slag2d (l)  converts a SINGLE PRECISION matrix, SA, to a DOUBLE PRECISION matrix, A
 slagtf (l)  factorizes the matrix (T  lambda*I), where T is an n by n tridiagonal matrix and lambda is a scalar, as T  lambda*I = PLU,
 slagtm (l)  performs a matrixvector product of the form B := alpha * A * X + beta * B where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or 1
 slagts (l)  may be used to solve one of the systems of equations (T  lambda*I)*x = y or (T  lambda*I)aq*x = y,
 slagv2 (l)  computes the Generalized Schur factorization of a real 2by2 matrix pencil (A,B) where B is upper triangular
 sla_gbamv (l)  performs one of the matrixvector operations y := alpha*abs(A)*abs(x) + beta*abs(y),