[REQ] Add opt-in setting to enable builtin approximates for wp.inverse and wp.division

[sarichardson-nv]

Description

Add an opt-in parameter: "use_rcp_approx", to disable/enable the explicit usage of the PTX intrinsic "div.approx" and "rcp.approx" for both FP32/FP64-based matrix inverses (wp.inverse) and division (wp.div).

i.e.
wp.div(a, b, use_rcp_approx = True)
wp.inverse(a, use_rcp_approx = True)

[shi-eric]

This is now available on main (e8106c0). Rather than adding an opt-in parameter to the existing wp.div() / wp.inverse(), we introduced two new built-in functions:

• wp.div_approx(a, b) — uses div.approx.f32 for float32; for float64, uses rcp.approx.ftz.f64 followed by a multiply (no div.approx.f64 exists in PTX)
• wp.inverse_approx(a) — uses rcp.approx.f32 for float32 and rcp.approx.ftz.f64 for float64

This approach keeps the semantics explicit: callers opt in by choosing a different function rather than toggling a flag. Both fall back to exact arithmetic on CPU. Only floating-point scalar types are supported.

Will ship in the 1.12.0 release.

[c0d1f1ed]

The merged changes look good but one thing worth noting is that it might be unexpected that float16 approximate division falls back to using full float32 division. It would make more sense to use the 32-bit div_approx. Not an immediate priority though.

[shi-eric]

The merged changes look good but one thing worth noting is that it might be unexpected that float16 approximate division falls back to using full float32 division. It would make more sense to use the 32-bit div_approx. Not an immediate priority though.

Sounds good, I'll prepare a change for this today so we don't have to risk confusing people with a behavior change in a future release.