gord(1)

💖 gord(1) — the Scotch user's manual, but make it a group chat 💖

okay bestie, sit DOWN, because today we're talking about gord, and she's iconic. this is page one of the Scotch user's manual and she's here to compute sparse matrix orderings of graphs. yes, that's the whole vibe. let's get into it 🌸

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✨ NAME ✨

gord — compute sparse matrix orderings of graphs. that's it, that's the girl. 🎀

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🦋 SYNOPSIS 🦋

gord [options] [gfile] [ofile] [lfile]

like, look at her. four slots. so clean. so demure. 💅

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🌈 DESCRIPTION 🌈

so here's the tea, bestie. the gord program computes, in a sequential way, an ordering of a Scotch source graph. and what source graph, you ask? one that represents the pattern of some symmetric sparse matrix. that's the assignment. she ate. no cap. ⭐

the source graph file gfile can only be a centralized graph file — that's the rule, don't fight it, she doesn't do distributed, she's a one-machine queen 👑

the resulting ordering gets stored in file ofile. and any eventual logging information (like the stuff that shows up when you turn on -v) goes off to file lfile. very demure, very mindful, everything has its own little home 🫶

when you don't specify file names? no stress. data gets read from standard input and written to standard output. and if you're feeling fancy and want to name your standard streams out loud, you can literally just use a dash '-' to represent them. so quirky, love that for her 💀

now here's the part that's giving main character energy: when the proper libraries have been included at compile time, gord can directly handle compressed graphs — both as input and output. a stream gets treated as compressed whenever its name is postfixed with a compressed file extension, like in 'brol.grf.bz2' or '- .gz'... okay wait, the original says '- .gz' — actually it's '-' plus .gz, you know what I mean, it's '-' postfixed with .gz, moving on bestie 😭

the compression formats that can be supported are:

• the bzip2 format ('.bz2')
• the gzip format ('.gz')
• the lzma format ('.lzma')

three formats. three little icons. we love a versatile queen 🧚

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💅 OPTIONS 💅

strap in, this is where it gets juicy. every single flag, no skips, periodt.

• -copt — choose your default ordering strategy based on one or SEVERAL of these options. mix and match, she's flexible:
  • b — enforce load balance as much as possible. balance is the moment ⚖️
  • d — manage disconnected graphs more efficiently. she's got range 🦋
  • q — privilege quality over speed. (this is the default!)
  • s — privilege speed over quality. fast girl era 🏃♀️
  • t — enforce safety. seatbelt ON 🎀
• -h — display some help. when you're lost, she's got you bestie 🫶
• -mmfile — save column block mapping data to file mfile. and what IS mapping data, you ask? it specifies, for each vertex, the index of the column block to which this vertex belongs. very specific. very precise. we stan a thorough queen 📌
• -ostrat — use sequential graph ordering strategy strat (go check the Scotch user's manual for more info, she said what she said)
• -ttfile — save partitioning tree data to file tfile. and partitioning tree data specifies, for each vertex, the index of the first vertex of the parent block of the block to which the vertex belongs. and here's the slay: altogether with the mapping data provided in file mfile, it lets you rebuild the separator tree of the nested dissection process. that's not just data, that's a whole reconstruction arc 🌟
• -V — display program version and copyright. respect the elders ✨
• -vverb — set verbose mode to verb. it's a set of one or more characters, which can be:
  • s — strategy information.
  • t — timing information. ⏱️

and yes, before anyone comes for me — the original really does spell it "explicitely". I'm not fixing it, I'm not renaming it, I'm just telling you it's there. we preserve, always 💖

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🍓 EXAMPLE 🍓

here's the classic. reorder matrix graph brol.grf and save the resulting ordering to file brol.ord, using the default sequential graph ordering strategy:

$ gord brol.grf brol.ord

one line. one slay. she's efficient 💅

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👑 SEE ALSO 👑

go say hi to the rest of the family:

• dgord(1)
• gmk_hy(1)
• gtst(1)
• the Scotch user's manual 📖

all icons, all connected, iykyk 🌈

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🌸 AUTHOR 🌸

Francois Pellegrini <francois.pellegrini@labri.fr> — the legend herself. thank you for your service 🫡💜

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and that's the whole page, bestie!!! this was gord(1) from the Scotch user's manual, dated 16 June 2026 🎀 like, that's the version, that's the source, that's the date, all accounted for. now go order some graphs and be the main character of your own sparse matrix 💖✨🦋