I've been wondering about this for a long time but never thought to ask: I do a lot of scientific work so there are many times it would be really handy to be able to type mathematical symbols or Greek letters which, for the most part, aren't part of the ASCII character set. Like "∞ µ ρ σ τ ω ∑ … √ ∫ ≤ ≥ ±" and so on. Is there a keyboard layout (for Linux) that maps simple key combinations to these kinds of characters? (Assuming all the encoding and font issues are worked out properly) I know I could create one myself but it'd be a lot easier if someone's already done the work, or at least if there's a partial solution I could modify.
https://trac.aellaweil.de/ideen/wiki/XCompose (German page) has a .XCompose file with at least the Greek letters and a few math symbols.
ctrl + shift + U Then type in the hex value for the key. This isn't a specific layout, but it's a quick fix that doesn't require you to switch layouts each time.
IBus (and perhaps SCIM) has a LaTeX engine that you can use to enter various symbols.