gesolver(1)

💖 gesolver(1) — the generalized eigensolver glow-up 💖

okay bestie, so this is the manual page for gesolver (utility commands section, iykyk). the actual program inside is called gesolve, which is a whole vibe — the page name and the program name are not the same, and that's just how it is, no notes. 🎀

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✨ NAME ✨

gesolve — an eigensolver for generalized eigenvalue problems. and when we say Ritz values only, we mean it: Ritz values only, nothing else. periodt. 💅

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✨ SYNOPSIS ✨

gesolve matrix_a_filename matrix_b_filename evalues_filename [options]

that's it, that's the whole summoning ritual. three filenames and then whatever options you're feeling. 🦋

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✨ DESCRIPTION ✨

so here's the tea, bestie. this program takes the matrix data in from matrix_a_filename and matrix_b_filename, and then it goes ahead and solves the generalized eigenvalue problem

A*x = l*B*x

using whichever solver you told it to use via the options. 👑

then it outputs the number of Ritz values you asked for — and that number comes from the -ss option, remember that — into evalues_filename, in the extended Matrix Market format (peep the Appendix of the Lis User Guide for the deets on that).

and here's the cute part: both the Matrix Market format and the Harwell-Boeing format are supported for the matrix filenames. so whichever one your matrices are living in, you're covered. 🌈

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✨ OPTIONS ✨

the following options are supported, and yes we're going through all of them, no skimming:

• -e eigensolver — picks your eigensolver. here are the options that are supported for eigensolver:
  • -e {gli|15} — Generalized Lanczos 🌸
    • -ss [1] — the size of the subspace
  • -e {gai|16} — Generalized Arnoldi 🦋
    • -ss [1] — the size of the subspace

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🌟 Other Options for eigensolver 🌟

• -eprint [0] — the output of the residual history
  • -eprint {none|0} — None (she's quiet, she's mysterious 💀)
  • -eprint {mem|1} — save the residual history
  • -eprint {out|2} — output it to the standard output
  • -eprint {all|3} — save the residual history and output it to the standard output (go big or go home 🫶)
• -omp_num_threads [t] — the number of the threads (t represents the maximum number of the threads)
• -estorage [0] — the matrix storage format
• -estorage_block [2] — the block size of the BSR and BSC formats
• -ef [0] — the precision of the eigensolver
  • -ef {double|0} — double precision
  • -ef {quad|1} — double-double (quadruple) precision ✨

heads up bestie: see the Lis User Guide for the full description. this page is giving highlights, not the whole novel. 📖

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✨ EXIT STATUS ✨

the following exit values are returned:

• 0 — the process is normally terminated 🎉 (slay, she finished clean)
• unspecified — an error occurred 😭 (not the vibe, something went wrong)

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✨ SEE ALSO ✨

go read these too, they're the friend group:

• lis(3)
• lsolve(1)
• gesolve(1)
• hpcg_kernel(1)
• hpcg_spmvtest(1)
• spmvtest1(1)
• spmvtest2(1)
• spmvtest2b(1)
• spmvtest3(1)
• spmvtest3b(1)
• spmvtest4(1)
• spmvtest5(1)

and the links, because we love a source:

• http://www.ssisc.org/lis/
• http://math.nist.gov/MatrixMarket/

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and that's the whole page, bestie!! it's a Man Page situation, and the version stamp on this one is 4 Nov 2017. yes, 2017. she's vintage, she's iconic, she still works. 🎀💖✨