1ZLACON(1)           LAPACK auxiliary routine (version 3.1)           ZLACON(1)
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NAME

6       ZLACON - the 1-norm of a square, complex matrix A
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SYNOPSIS

9       SUBROUTINE ZLACON( N, V, X, EST, KASE )
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11           INTEGER        KASE, N
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13           DOUBLE         PRECISION EST
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15           COMPLEX*16     V( N ), X( N )
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PURPOSE

18       ZLACON  estimates  the  1-norm  of a square, complex matrix A.  Reverse
19       communication is used for evaluating matrix-vector products.
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ARGUMENTS

23       N      (input) INTEGER
24              The order of the matrix.  N >= 1.
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26       V      (workspace) COMPLEX*16 array, dimension (N)
27              On the final return, V = A*W,  where  EST =  norm(V)/norm(W)  (W
28              is not returned).
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30       X      (input/output) COMPLEX*16 array, dimension (N)
31              On  an  intermediate  return,  X should be overwritten by A * X,
32              if KASE=1, A' * X,  if KASE=2, where A' is the conjugate  trans‐
33              pose  of  A,  and  ZLACON  must  be re-called with all the other
34              parameters unchanged.
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36       EST    (input/output) DOUBLE PRECISION
37              On entry with KASE = 1  or  2  and  JUMP  =  3,  EST  should  be
38              unchanged  from the previous call to ZLACON.  On exit, EST is an
39              estimate (a lower bound) for norm(A).
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41       KASE   (input/output) INTEGER
42              On the initial call to ZLACON, KASE should be 0.  On an interme‐
43              diate  return,  KASE will be 1 or 2, indicating whether X should
44              be overwritten by A * X  or A' * X.  On the  final  return  from
45              ZLACON, KASE will again be 0.
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FURTHER DETAILS

48       Contributed by Nick Higham, University of Manchester.
49       Originally named CONEST, dated March 16, 1988.
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51       Reference: N.J. Higham, "FORTRAN codes for estimating the one-norm of a
52       real or complex matrix, with applications to condition estimation", ACM
53       Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.
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55       Last modified:  April, 1999
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60 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       ZLACON(1)