clacon.f(3)

NAME
clacon.f

SYNOPSIS

  Functions/Subroutines
subroutine clacon (N, V, X, EST, KASE)
CLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products.

Function/Subroutine Documentation

  subroutine clacon (integer N, complex, dimension( n ) V, complex, dimension( n ) X, real EST, integer KASE)

Purpose:

     CLACON estimates the 1-norm of a square, complex matrix A.
     Reverse communication is used for evaluating matrix-vector products.

Parameters
    N

              N is INTEGER
             The order of the matrix.  N >= 1.

    V

              V is COMPLEX array, dimension (N)
             On the final return, V = A*W,  where  EST = norm(V)/norm(W)
             (W is not returned).

    X

              X is COMPLEX array, dimension (N)
             On an intermediate return, X should be overwritten by
                   A * X,   if KASE=1,
                   A**H * X,  if KASE=2,
             where A**H is the conjugate transpose of A, and CLACON must be
             re-called with all the other parameters unchanged.

    EST

              EST is REAL
             On entry with KASE = 1 or 2 and JUMP = 3, EST should be
             unchanged from the previous call to CLACON.
             On exit, EST is an estimate (a lower bound) for norm(A).

    KASE

              KASE is INTEGER
             On the initial call to CLACON, KASE should be 0.
             On an intermediate return, KASE will be 1 or 2, indicating
             whether X should be overwritten by A * X  or A**H * X.
             On the final return from CLACON, KASE will again be 0.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Further Details:
    Originally named CONEST, dated March 16, 1988.
     Last modified: April, 1999

Contributors:
    Nick Higham, University of Manchester

References:
    N.J. Higham, 'FORTRAN codes for estimating the one-norm of
      a real or complex matrix, with applications to condition estimation', ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.

Definition at line 113 of file clacon.f.

Author

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