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clacon

 NAME
      CLACON - estimate the 1-norm of a square, complex matrix A

 SYNOPSIS
      SUBROUTINE CLACON( N, V, X, EST, KASE )

          INTEGER        KASE, N

          REAL           EST

          COMPLEX        V( N ), X( N )

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

 ARGUMENTS
      N      (input) INTEGER
             The order of the matrix.  N >= 1.

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

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

      EST    (output) REAL
             An estimate (a lower bound) for norm(A).

      KASE   (input/output) INTEGER
             On the initial call to CLACON, KASE should be 0.  On
             an intermediate return, KASE will be 1 or 2, indicat-
             ing whether X should be overwritten by A * X  or A' *
             X.  On the final return from CLACON, KASE will again
             be 0.

 FURTHER DETAILS
      Contributed by Nick Higham, University of Manchester.
      Originally named CONEST, dated March 16, 1988.

      Reference: 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.