SRC/zlacon.f(3)

🎀 NAME

SRC/zlacon.f — from the Library Functions Manual (manual name folded in near the top like a little bow, periodt 🎀).

✨ SYNOPSIS

Functions/Subroutines

• subroutine zlacon (n, v, x, est, kase) — ZLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products.

🦋 Function/Subroutine Documentation

subroutine zlacon (...)

subroutine zlacon (integer n, complex*16, dimension( n ) v, complex*16, dimension( n ) x, double precision est, integer kase)

ZLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products. Yes bestie, that's the whole assignment. 💅

🌸 Purpose

okay so ZLACON estimates the 1-norm of a square, complex matrix A. Reverse communication is used for evaluating matrix-vector products. That's the vibe: you handle the matrix-vector products, and ZLACON keeps the estimate situation going.

💅 Parameters

• N — 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.

bestie, this is reverse-communication core: when KASE comes back as 1 or 2, you do the matching product into X and call ZLACON again with all the other parameters unchanged. That part is literally not optional. 💀

👑 Author

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

🌈 Further Details

Originally named CONEST, dated March 16, 1988. Last modified: April, 1999.

🍓 Contributors

Nick Higham, University of Manchester.

🔥 References

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.

Definition at line 113 of file zlacon.f.

🧚 Author

Generated automatically by Doxygen for LAPACK from the source code.

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okay bye bestie 💋 — this page is LAPACK Version 3.12.0 for SRC/zlacon.f(3), and the source's last-modified date is April, 1999. 🫶✨