CustomBaseLogarithm

CustomBaseLogarithm is PredefinedLogarithm with the training wheels off. Instead of picking e, 10, or 2, you type any base from 1.1 upward and the node computes log_base(sigma) for every value in your schedule. The closer your base is to 1.1, the gentler the compression; a larger base squeezes the range more aggressively. It's the fine-grained version of "put this schedule into log space so its shape is actually editable."

And that's the real job, same as its predefined sibling: schedules spanning orders of magnitude (like real sigma runs, 0.03 to 14.7) are all but impossible to reason about raw - the low end is a whisper next to the high end. In log space the differences become visible and tunable. This node is the compression step; CustomExponent is the decompression that gets you back.

How it works

For each sigma value it computes math.log(sigma, base). Order is preserved (logs are monotonic), so the character of your curve survives the trip - the values just get packed together. There's no clamping, no handling for non-positive input; feed it a schedule with a zero in it and the math breaks, because you can't take a logarithm of zero or a negative.

The inputs and output

• sigmas - the schedule to compress into log space.
• base (2.0, min 1.1, step 0.1) - the log base. Closer to 1.1 is gentler compression; higher is stronger.
• Output: SIGMAS - the log-transformed array.

Install

Part of ComfyUI-ScheduledGuider-Ext. ComfyUI Manager - search ComfyUI-ScheduledGuider-Ext - or:

cd ComfyUI/custom_nodes
git clone https://github.com/mfg637/ComfyUI-ScheduledGuider-Ext

Restart ComfyUI. No models, no extra dependencies.

Common issues

Two traps, both inherited from the family. First, the zero problem: a schedule with a trailing 0 (the default sigma_min of 0 in this pack's own schedulers!) can't be logged. Set the minimum above zero before transforming, or drop the offending value. Second, the round-trip requires matching bases - compress at base 2.5 and you must decompress at base 2.5 to get back what you started with. Mismatched bases are the classic silent mistake, because nothing errors; the numbers just quietly end up somewhere else.

Beyond that, this is a fiddly little math tool with a narrow job. If you're not actively editing a schedule in log space, you don't need it - and that's fine. It's here for the workflows that do, and it does that job cleanly.