ZLACON estimates the 1-norm of a square, complex matrix A.


 Reverse communication is used for evaluating matrix-vector products.

N

          N is INTEGER


         The order of the matrix.  N >= 1.

V

          V is COMPLEX*16 array, dimension (N)


         On the final return, V = A*W,  where  EST = norm(V)/norm(W)


         (W is not returned).

X

          X is COMPLEX*16 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 ZLACON must be


         re-called with all the other parameters unchanged.

EST

          EST is DOUBLE PRECISION


         On entry with KASE = 1 or 2 and JUMP = 3, EST should be


         unchanged from the previous call to ZLACON.


         On exit, EST is an estimate (a lower bound) for norm(A). 

KASE

          KASE is INTEGER


         On the initial call to ZLACON, 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 ZLACON, KASE will again be 0.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

September 2012

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

Nick Higham, University of Manchester

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.