SRC/slacon.f(3)

🎀 NAME

okay so SRC/slacon.f — from the Library Functions Manual, bestie. That’s the name, no cap. 💅

✨ SYNOPSIS

🧚 Functions/Subroutines

• subroutine slacon (n, v, x, isgn, est, kase) — SLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products. Iconic behavior, honestly.

💖 Function/Subroutine Documentation

subroutine slacon (integer n, real, dimension( * ) v, real, dimension( * )
       x, integer, dimension( * ) isgn, real est, integer kase)

SLACON estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vector products. Main character numerical subroutine energy, fr fr.

🎯 Purpose:

SLACON estimates the 1-norm of a square, real matrix A. Reverse communication is used for evaluating matrix-vector products. That’s the purpose, and it ate. ✨

🧩 Parameters

• N — N is INTEGER. The order of the matrix. N >= 1. Keep it legal, bestie.
• V — V is REAL array, dimension (N). On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned). W is the friend who did not make it into the group photo. 😭
• X — X is REAL array, dimension (N). On an intermediate return, X should be overwritten by A * X, if KASE=1; by A**T * X, if KASE=2; and SLACON must be re-called with all the other parameters unchanged. No cap, literally overwrite it and call her back.
• ISGN — ISGN is INTEGER array, dimension (N). She gets her own line and her own little moment. 🎀
• EST — EST is REAL. On entry with KASE = 1 or 2 and JUMP = 3, EST should be unchanged from the previous call to SLACON. On exit, EST is an estimate (a lower bound) for norm(A). Lower bound is serving.
• KASE — KASE is INTEGER. On the initial call to SLACON, 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**T * X. On the final return from SLACON, KASE will again be 0. The 0 → 1/2 → 0 pipeline is iconic. 👑

👑 Author

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

🌟 Contributors:

Nick Higham, University of Manchester. Originally named SONEST, dated March 16, 1988. We love a glow-up with receipts. 💖

📚 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. Cite her, bestie.

Definition at line 114 of file slacon.f.

🪄 Author

Generated automatically by Doxygen for LAPACK from the source code. (Not me, not you — Doxygen did that.)

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Cute sign-off: LAPACK Version 3.12.0 · SRC/slacon.f(3) · date: not listed separately in the footer, so we’re not inventing one, periodt. 🫶