SORT01 checks that the matrix U is orthogonal by computing the ratio


    RESID = norm( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R',


 or


    RESID = norm( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'.


 Alternatively, if there isn't sufficient workspace to form


 I - U*U' or I - U'*U, the ratio is computed as


    RESID = abs( I - U*U' ) / ( n * EPS ), if ROWCOL = 'R',


 or


    RESID = abs( I - U'*U ) / ( m * EPS ), if ROWCOL = 'C'.


 where EPS is the machine precision.  ROWCOL is used only if m = n;


 if m > n, ROWCOL is assumed to be 'C', and if m < n, ROWCOL is


 assumed to be 'R'.

ROWCOL

          ROWCOL is CHARACTER


          Specifies whether the rows or columns of U should be checked


          for orthogonality.  Used only if M = N.


          = 'R':  Check for orthogonal rows of U


          = 'C':  Check for orthogonal columns of U

M

          M is INTEGER


          The number of rows of the matrix U.

N

          N is INTEGER


          The number of columns of the matrix U.

U

          U is REAL array, dimension (LDU,N)


          The orthogonal matrix U.  U is checked for orthogonal columns


          if m > n or if m = n and ROWCOL = 'C'.  U is checked for


          orthogonal rows if m < n or if m = n and ROWCOL = 'R'.

LDU

          LDU is INTEGER


          The leading dimension of the array U.  LDU >= max(1,M).

WORK

          WORK is REAL array, dimension (LWORK)

LWORK

          LWORK is INTEGER


          The length of the array WORK.  For best performance, LWORK


          should be at least N*(N+1) if ROWCOL = 'C' or M*(M+1) if


          ROWCOL = 'R', but the test will be done even if LWORK is 0.

RESID

          RESID is REAL


          RESID = norm( I - U * U' ) / ( n * EPS ), if ROWCOL = 'R', or


          RESID = norm( I - U' * U ) / ( m * EPS ), if ROWCOL = 'C'.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.