SuperLU  5.0
Macros | Functions
dlacon.c File Reference

Estimates the 1-norm. More...

#include <math.h>
#include "slu_Cnames.h"
Include dependency graph for dlacon.c:

Macros

#define d_sign(a, b)   (b >= 0 ? fabs(a) : -fabs(a)) /* Copy sign */
 
#define i_dnnt(a)   ( a>=0 ? floor(a+.5) : -floor(.5-a) ) /* Round to nearest integer */
 

Functions

int dlacon_ (int *n, double *v, double *x, int *isgn, double *est, int *kase)
 

Detailed Description

– SuperLU routine (version 2.0) –
Univ. of California Berkeley, Xerox Palo Alto Research Center,
and Lawrence Berkeley National Lab.
November 15, 1997

Macro Definition Documentation

#define d_sign (   a,
 
)    (b >= 0 ? fabs(a) : -fabs(a)) /* Copy sign */
#define i_dnnt (   a)    ( a>=0 ? floor(a+.5) : -floor(.5-a) ) /* Round to nearest integer */

Function Documentation

int dlacon_ ( int *  n,
double *  v,
double *  x,
int *  isgn,
double *  est,
int *  kase 
)

Purpose

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

Arguments

  N      (input) INT
         The order of the matrix.  N >= 1.
  V      (workspace) DOUBLE 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 PRECISION array, dimension (N)   
         On an intermediate return, X should be overwritten by   
               A * X,   if KASE=1,   
               A' * X,  if KASE=2,
        and DLACON must be re-called with all the other parameters   
         unchanged.
  ISGN   (workspace) INT array, dimension (N)
  EST    (output) DOUBLE PRECISION   
         An estimate (a lower bound) for norm(A).
  KASE   (input/output) INT
         On the initial call to DLACON, 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 DLACON, 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.

 

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