sgqrts.f - Man Page

subroutine sgqrts (n, m, p, a, af, q, r, lda, taua, b, bf, z, t, bwk, ldb, taub, work, lwork, rwork, result)
SGQRTS

SGQRTS

Purpose:

 SGQRTS tests SGGQRF, which computes the GQR factorization of an
 N-by-M matrix A and a N-by-P matrix B: A = Q*R and B = Q*T*Z.

Parameters

N

          N is INTEGER
          The number of rows of the matrices A and B.  N >= 0.

M

          M is INTEGER
          The number of columns of the matrix A.  M >= 0.

P

          P is INTEGER
          The number of columns of the matrix B.  P >= 0.

A

          A is REAL array, dimension (LDA,M)
          The N-by-M matrix A.

AF

          AF is REAL array, dimension (LDA,N)
          Details of the GQR factorization of A and B, as returned
          by SGGQRF, see SGGQRF for further details.

Q

          Q is REAL array, dimension (LDA,N)
          The M-by-M orthogonal matrix Q.

R

          R is REAL array, dimension (LDA,MAX(M,N))

LDA

          LDA is INTEGER
          The leading dimension of the arrays A, AF, R and Q.
          LDA >= max(M,N).

TAUA

          TAUA is REAL array, dimension (min(M,N))
          The scalar factors of the elementary reflectors, as returned
          by SGGQRF.

B

          B is REAL array, dimension (LDB,P)
          On entry, the N-by-P matrix A.

BF

          BF is REAL array, dimension (LDB,N)
          Details of the GQR factorization of A and B, as returned
          by SGGQRF, see SGGQRF for further details.

Z

          Z is REAL array, dimension (LDB,P)
          The P-by-P orthogonal matrix Z.

T

          T is REAL array, dimension (LDB,max(P,N))

BWK

          BWK is REAL array, dimension (LDB,N)

LDB

          LDB is INTEGER
          The leading dimension of the arrays B, BF, Z and T.
          LDB >= max(P,N).

TAUB

          TAUB is REAL array, dimension (min(P,N))
          The scalar factors of the elementary reflectors, as returned
          by SGGRQF.

WORK

          WORK is REAL array, dimension (LWORK)

LWORK

          LWORK is INTEGER
          The dimension of the array WORK, LWORK >= max(N,M,P)**2.

RWORK

          RWORK is REAL array, dimension (max(N,M,P))

RESULT

          RESULT is REAL array, dimension (4)
          The test ratios:
            RESULT(1) = norm( R - Q'*A ) / ( MAX(M,N)*norm(A)*ULP)
            RESULT(2) = norm( T*Z - Q'*B ) / (MAX(P,N)*norm(B)*ULP)
            RESULT(3) = norm( I - Q'*Q ) / ( M*ULP )
            RESULT(4) = norm( I - Z'*Z ) / ( P*ULP )

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 174 of file sgqrts.f.