slags2 (3)  Linux Manuals
NAME
slags2.f 
SYNOPSIS
Functions/Subroutines
subroutine slags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ)
SLAGS2 computes 2by2 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 (logicalUPPER, realA1, realA2, realA3, realB1, realB2, realB3, realCSU, realSNU, realCSV, realSNV, realCSQ, realSNQ)
SLAGS2 computes 2by2 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 2by2 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:

UPPER
UPPER is LOGICAL = .TRUE.: the input matrices A and B are upper triangular. = .FALSE.: the input matrices A and B are lower triangular.
A1A1 is REAL
A2A2 is REAL
A3A3 is REAL On entry, A1, A2 and A3 are elements of the input 2by2 upper (lower) triangular matrix A.
B1B1 is REAL
B2B2 is REAL
B3B3 is REAL On entry, B1, B2 and B3 are elements of the input 2by2 upper (lower) triangular matrix B.
CSUCSU is REAL
SNUSNU is REAL The desired orthogonal matrix U.
CSVCSV is REAL
SNVSNV is REAL The desired orthogonal matrix V.
CSQCSQ is REAL
SNQSNQ is REAL 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 slags2.f.
Author
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