Sigmas Abs

Sigmas Abs is the cleanup crew of RES4LYF's sigma toolbox. It does one thing: take every value in a noise schedule and make it positive if it isn't already. Simple, but it earns its place - a lot of the pack's other sigma nodes are perfectly happy to hand you a schedule with negative values in it, and a sampler is not.

Why negative sigmas happen

A SIGMAS list represents noise levels, which are supposed to be non-negative by definition. But RES4LYF ships a lot of nodes that generate or transform sigma values through arbitrary math - Sigmas2 Add, Sigmas2 Mult, the arc-trig reshaping nodes, the chaos and attractor generators - and none of that math has a built-in guarantee it'll stay in positive territory. Subtract two curves, run something through an inverse-tangent, iterate a chaotic map: any of these can dip below zero, and a sampler fed a negative sigma is likely to misbehave or throw a NaN.

How it works

Absolute value, applied elementwise: every negative value flips to positive, everything already positive is untouched. That's the entire operation.

The inputs and outputs that matter

One required input, sigmas (SIGMAS), one output, SIGMAS. Nothing to configure.

How to install it

• ComfyUI Manager - search "RES4LYF", install, restart.
• Manual - activate your venv, cd ComfyUI/custom_nodes && git clone https://github.com/ClownsharkBatwing/RES4LYF, cd RES4LYF, pip install -r requirements.txt (portable builds: point at the embedded pip.exe instead). Restart ComfyUI.

Common issues & troubleshooting

It fixes sign, not shape. Flipping a negative value positive doesn't put a schedule back into a sensible decreasing order - a curve that dipped negative and got flipped can end up with a bump in the middle instead of a smooth descent. If your renders still look wrong after adding this node, the problem is probably that the schedule isn't monotonic anymore, not that it's negative. Sigmas CatmullRom (spline smoothing) or a rethink of whatever math produced the schedule in the first place is the next step.

It's a bandage, not a validator. This node will happily take a schedule that's negative because of a genuine mistake upstream (mismatched list lengths in an add/mult node, say) and paper over it rather than surface the error. Worth checking the actual numbers - wire in Sigmas Count for the step count, or preview the raw values - before trusting a hand-built schedule on a real render, rather than reaching for Abs as the only fix.

Not documented anywhere. Like the rest of RES4LYF's sigma-manipulation nodes, this isn't covered in the README beyond the general note that the category is experimental. There's no community write-up recommending a specific chain that includes it - it's just the obvious tool once you notice you need it.