All right, we just went thru the JS Math object and reviewed every single function for inclusion into CSS. Results:

Adding: * round(), with keywords to select rounding behavior (nearest, up, down, toward-zero) * mod(), with an issue to decide later whether we use JS or math semantics for negative values * sign() (numbers only) * abs() * exp() * log() * e and pi, as keywords in math funcs

Not adding: * cbrt() (no real use-case, can add later if needed) * hyperbolic trig functions (same) * the other constants (same) * fround(), clz32(), imul() (weird bit stuff) * random() (totally distinct feature, v complicated) * the log() and exp() variants (just use math)

And that's everything. Now that we have the e and pi precedent, we'll discuss adding infinity (and maybe -infinity?) as constants after the break (right now you have to spell them as 1/0 or -1/0 when serializing, which is weird).

Heck, let's straw-poll the mod issue: What should be the answer to mod(-8px, 5px)? (feel free to RT for reach)

That's gonna get really odd if 0 is in the middle of the range and half way through the behavior changes.

Can you elaborate?

A weird an stupid example: Someone is using it to adjust the width of a box according to it's left position so that it always snaps to 5px. As the box pans left and right it works fine until it goes off the left of it's container and starts getting a negative width.