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Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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clacon(l) |
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CLACON - estimate the 1-norm of a square, complex matrix A
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SUBROUTINE CLACON( |
N, V, X, EST, KASE ) |
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INTEGER |
KASE, N |
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REAL |
EST |
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COMPLEX |
V( N ), X( N ) |
CLACON estimates the 1-norm of a square, complex matrix A. Reverse communication is used for evaluating matrix-vector products.
N (input) INTEGER
The order of the matrix. N >= 1.
V (workspace) COMPLEX array, dimension (N)
On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned).
X (input/output) COMPLEX 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 CLACON must be re-called with all the other parameters unchanged.
EST (output) REAL
An estimate (a lower bound) for norm(A).
KASE (input/output) INTEGER
On the initial call to CLACON, 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 CLACON, KASE will again be 0.
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.
Last modified: April, 1999
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clacon(l) | |