Sigmas2 Add

This is one of RES4LYF's sigma-math nodes - the toolbox behind the pack's stated goal of letting you shape a noise schedule by hand instead of picking one off a preset list. Sigmas2 Add does exactly what the name says: it takes two sigma schedules and adds them together, value by value.

What sigmas actually are, quickly

A SIGMAS output is the list of noise levels a sampler steps through - normally produced by a scheduler node like BasicScheduler or KarrasScheduler, starting high and decreasing to (near) zero across however many steps you asked for. Most nodes downstream just take that list on faith. RES4LYF's sigma toolbox is for the people who want to build or edit that list directly.

How it works

Straightforward elementwise addition: the first value of sigmas_1 plus the first value of sigmas_2, the second plus the second, and so on, producing one output list the same length as the inputs. That's the whole mechanism - there's no smoothing, clamping, or reordering involved.

The inputs and outputs that matter

Both inputs are required and both are plain SIGMAS: sigmas_1 and sigmas_2. There's nothing else to configure. The single output, SIGMAS, is the sum, ready to plug into a sampler that takes a custom sigmas input (RES4LYF's own ClownsharKSampler explicitly supports this - hook a schedule into its SIGMAS input and it overrides the built-in scheduler and step count entirely) or into another sigma-math node further down the chain.

The obvious use is layering: take a base schedule from a normal scheduler node and add a small hand-built perturbation curve on top of it, rather than blending the two proportionally the way a scheduler-swap or Sigmas2 Mult would.

How to install it

• ComfyUI Manager - search "RES4LYF", install, restart.
• Manual - activate your venv (source venv/bin/activate on Linux, venv\Scripts\activate on Windows), then cd ComfyUI/custom_nodes && git clone https://github.com/ClownsharkBatwing/RES4LYF, cd RES4LYF, and pip install -r requirements.txt. On the portable build, swap pip for the path to your embedded Python's pip.exe. Restart ComfyUI.

Common issues & troubleshooting

The two schedules need to be the same length. Elementwise addition has no defined behavior for mismatched lengths, and nothing in the pack documents what happens if you feed it two lists of different sizes. Easiest fix: generate both sigmas_1 and sigmas_2 from schedulers set to the same step count.

The result isn't guaranteed to still be a valid schedule. Sigma schedules are supposed to be non-negative and generally decreasing across the run - a sampler assumes that shape. Add two arbitrary schedules and you can easily end up with a curve that jumps around or dips negative, which most samplers won't handle gracefully. If that happens, run the output through Sigmas Abs to fix negative values, or Sigmas Cleanup to enforce a noise floor, before wiring it into a real sampler.

No documented use case. The README covers RES4LYF's flagship sampler nodes in detail but says nothing about this specific tool beyond framing the whole sigma-manipulation category as "experimental and subject to further changes." Treat it as raw material: cheap to test on a low-res, low-step generation first, before trusting it on a render you actually care about.