Batch Float Math (mtb)

Once you're building animation curves out of MTB's FLOATS - those per-frame lists that drive pan, zoom and rotate - you eventually want to combine two of them. Add a slow drift onto a fast wobble. Multiply a curve by an envelope so it fades in. Subtract one from another. Batch Float Math is the little arithmetic node that does that, operating element-by-element across the float streams you wire in.

It's unglamorous plumbing, but it's the difference between hand-authoring every curve and composing them from simpler pieces. Layered motion - a gentle overall push with a subtle handheld shake on top - is just two curves and an add.

How it works

It runs one arithmetic operation across the float inputs you connect, pairing up values by position: result at frame 0 is a[0] op b[0], frame 1 is a[1] op b[1], and so on. The operation is picked from a dropdown, and there's a reverse switch for the operations where order matters.

The inputs and outputs that matter

• operation - add, sub, mul, div, pow, or abs. Add and multiply are the everyday ones (layer curves, apply an envelope); abs folds negatives positive; pow shapes a curve's steepness.
• reverse (default false) - flips the operand order. Irrelevant for add and mul (they're commutative), but it changes the result for sub, div, and pow - so if your subtraction or division came out backwards, this is the toggle.

The output is a FLOATS curve you feed onward to Batch2d Transform, Auto Pan, or another batch-float node. (You supply the float streams it operates on by wiring them into the node.)

How to install it

Via ComfyUI Manager: search MTB Nodes, install, restart. Or manually:

cd ComfyUI/custom_nodes
git clone https://github.com/melMass/comfy_mtb

then restart. No models - it's arithmetic.

Common issues & troubleshooting

The result looks backwards. For sub, div, and pow, the order of the two curves matters - a - b isn't b - a. Flip reverse instead of re-wiring your inputs.

The two curves are different lengths. Element-wise math wants matching lengths. If one curve is shorter, pad it to length first (Batch Float Fill) so the operation lines up frame-for-frame instead of stopping early or misaligning.

Divide-by-zero weirdness. If a div produces infinities or NaNs, check that the second curve never hits zero at any frame. Add a small constant, or clamp it first with Batch Float Fit.

It's part of a family. On its own this node isn't much. It shines composed with the others: build base curves, remap them with Batch Float Fit, combine them here, then drive Batch2d Transform. That's the MTB animation loop.