subroutine zlacon (N, V, X, EST, KASE)
subroutine zlacon (integerN, complex*16, dimension( n )V, complex*16, dimension( n )X, double precisionEST, integerKASE)ZLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products. Purpose:
ZLACON estimates the 1-norm of a square, complex matrix A. Reverse communication is used for evaluating matrix-vector products.
N is INTEGER The order of the matrix. N >= 1.V
V is COMPLEX*16 array, dimension (N) On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned).X
X 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 re-called with all the other parameters unchanged.EST
EST 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).KASE
KASE 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.
Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.Date:
September 2012Further Details:
Originally named CONEST, dated March 16, 1988.Contributors:
Last modified: April, 1999
Nick Higham, University of ManchesterReferences:
N.J. Higham, 'FORTRAN codes for estimating the one-norm ofDefinition at line 115 of file zlacon.f.
a real or complex matrix, with applications to condition estimation', ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.