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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine clacn2 | ( | integer | N, |
complex, dimension( * ) | V, | ||
complex, dimension( * ) | X, | ||
real | EST, | ||
integer | KASE, | ||
integer, dimension( 3 ) | ISAVE | ||
) |
CLACN2 estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products.
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CLACN2 estimates the 1-norm of a square, complex matrix A. Reverse communication is used for evaluating matrix-vector products.
[in] | N | N is INTEGER The order of the matrix. N >= 1. |
[out] | V | V is COMPLEX array, dimension (N) On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned). |
[in,out] | X | X is COMPLEX 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 CLACN2 must be re-called with all the other parameters unchanged. |
[in,out] | EST | EST is REAL On entry with KASE = 1 or 2 and ISAVE(1) = 3, EST should be unchanged from the previous call to CLACN2. On exit, EST is an estimate (a lower bound) for norm(A). |
[in,out] | KASE | KASE is INTEGER On the initial call to CLACN2, 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 CLACN2, KASE will again be 0. |
[in,out] | ISAVE | ISAVE is INTEGER array, dimension (3) ISAVE is used to save variables between calls to SLACN2 |
Originally named CONEST, dated March 16, 1988. Last modified: April, 1999 This is a thread safe version of CLACON, which uses the array ISAVE in place of a SAVE statement, as follows: CLACON CLACN2 JUMP ISAVE(1) J ISAVE(2) ITER ISAVE(3)
Definition at line 135 of file clacn2.f.