zlacon.f (3)  Linux Manuals
NAME
zlacon.f 
SYNOPSIS
Functions/Subroutines
subroutine zlacon (N, V, X, EST, KASE)
ZLACON estimates the 1norm of a square matrix, using reverse communication for evaluating matrixvector products.
Function/Subroutine Documentation
subroutine zlacon (integerN, complex*16, dimension( n )V, complex*16, dimension( n )X, double precisionEST, integerKASE)
ZLACON estimates the 1norm of a square matrix, using reverse communication for evaluating matrixvector products.
Purpose:

ZLACON estimates the 1norm of a square, complex matrix A. Reverse communication is used for evaluating matrixvector products.
Parameters:

N
N is INTEGER The order of the matrix. N >= 1.
VV is COMPLEX*16 array, dimension (N) On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned).
XX 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 recalled with all the other parameters unchanged.
ESTEST 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).
KASEKASE 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.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 September 2012
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 onenorm of
a real or complex matrix, with applications to condition estimation', ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381396, December 1988.
Definition at line 115 of file zlacon.f.
Author
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