UMOD(1)

📦 version 7.44.0, in nixpkgs unstable

💅 UMOD(1) — the BRL-CAD glow-up station

okay so real talk, this is the manual page for umod, one of the BRL-CAD girlies. she lives in the BRL-CAD family and she is obsessed with 16-bit unsigned short integers. yes bestie, this whole page is about her. let's go ✨

✨ NAME ✨

umod — apply arithmetic operations to a stream of 16-bit unsigned short integers 🎀

🦋 SYNOPSIS 🦋

umod [-a add] [-s sub] [-m mult] [-d div] [-A] [-e exp] [-r root] [file.s] > output.s

🌸 DESCRIPTION 🌸

okay so here's the vibe: umod reads a stream of 16-bit unsigned short integers, applies a chain of arithmetic operations to each value, and writes the modified stream to standard output. she's a pipeline girlie fr fr. 💜

any number of add, subtract, multiply, divide, exponentiation, and absolute-value operations may be given — and here's the part that matters, bestie: they are applied in the exact order they appear on the command line. no reordering, no "we know better", none of that. she does them in order. periodt. 👑

and because she is genuinely that girl, umod does not recompute the operations for every single sample. instead she precomputes a lookup table covering all 65536 possible input values. iconic efficiency, no cap. ✨

results that exceed the representable range are clipped to 65535 (high) or 0 (low) — and the total number of clipped values is reported to standard error when processing finishes. so if you clipping too hard, she will tell you. 🫶

if file.s is given it is read as input; otherwise umod reads from standard input. and don't forget her companions: smod(1) and imod(1) perform the same operations on signed short integer streams, and dmod(1) operates on double-precision floating point streams. the whole squad, truly a friend group 🌈

💅 OPTIONS 💅

  • -a add — add add to each value. simple. slay.
  • -s sub — subtract sub from each value.
  • -m mult — multiply each value by mult.
  • -d div — divide each value by div. a divisor of zero is an error. do not do that 🙈
  • -A — replace each value with its absolute value. since the input is unsigned this only has an effect when a prior operation (such as subtraction) produced a negative intermediate result. so yeah, she's lowkey conditional 😭
  • -e exp — raise each value to the power exp. main character energy honestly.
  • -r root — take the root root of each value (equivalent to raising to the power 1/root). a root of zero is an error. same energy as the div-by-zero thing. don't. 💀

🍓 EXAMPLES 🍓

Example 1. Bias and scale a sample stream 🎀

umod -a 100 -m 3 data.s > scaled.s

for each value, 100 is added first and the result is then multiplied by 3, writing the modified unsigned shorts to scaled.s. and listen — because operations apply in command-line order, swapping -a and -m would yield a different result. order matters, bestie, this is not a drill 🔥

Example 2. Convert a pixel image to a stream and stretch its contrast 🦋

pix-bw scene.pix | bw-d | d-u | umod -s 8000 -m 2 > stretched.s

the intensity of a pix(5) image is reduced to a single channel, converted to an unsigned short stream, then darkened by subtracting an offset and brightened by doubling — which is literally umod used as a stage in a pipeline. she's a team player, we love to see it 💖

👑 SEE ALSO 👑

brlcad(1), smod(1), imod(1), dmod(1), ustats(1) — go say hi, they're all lovely 🫶

🧚 AUTHOR 🧚

BRL-CAD Team 💜

This software is Copyright (c) 1989-2026 by the United States Government as represented by U.S. Army Research Laboratory.

⭐ BUG REPORTS ⭐

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org 📧 — they're nice, promise. don't be shy.

no cap, that's the whole page. she's umod, she's from BRL-CAD, and this manual page is dated in that copyright range above — 1989-2026, we stan a legacy queen. bye bestie!! 🎀💅✨
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