SuperLU 6.0.1
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Estimates the 1-norm. More...
Functions | |
int | zlacon2_ (int *n, doublecomplex *v, doublecomplex *x, double *est, int *kase, int isave[3]) |
Copyright (c) 2003, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from U.S. Dept. of Energy)
All rights reserved.
The source code is distributed under BSD license, see the file License.txt at the top-level directory.
-- SuperLU routine (version 5.0) -- Univ. of California Berkeley, Xerox Palo Alto Research Center, and Lawrence Berkeley National Lab. July 24, 2022
int zlacon2_ | ( | int * | n, |
doublecomplex * | v, | ||
doublecomplex * | x, | ||
double * | est, | ||
int * | kase, | ||
int | isave[3] | ||
) |
Purpose ======= ZLACON2 estimates the 1-norm of a square matrix A. Reverse communication is used for evaluating matrix-vector products. This is a thread safe version of CLACON, which uses the array ISAVE in place of a STATIC variables, as follows: ZLACON ZLACON2 jump isave[0] j isave[1] iter isave[2] Arguments ========= N (input) INT The order of the matrix. N >= 1. V (workspace) DOUBLE COMPLEX PRECISION array, dimension (N) On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned). X (input/output) DOUBLE COMPLEX PRECISION 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 ZLACON must be re-called with all the other parameters unchanged. EST (output) DOUBLE PRECISION An estimate (a lower bound) for norm(A). KASE (input/output) INT 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' * X. On the final return from ZLACON, KASE will again be 0. isave (input/output) int [3] ISAVE is INTEGER array, dimension (3) ISAVE is used to save variables between calls to ZLACON2 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. =====================================================================