Erm, just what is this object? The documentation for it (in all locations) appears to be exactly the same as Gen~ sah. Is it exactly the same? If it is, why have it? Is it similar, but different? If so, how so? Is it something else entirely?
It doesn’t seem to take the same arguments as Sah, and I can’t seem to make it a valid object when instantiating…
Actually [interp @mode spline]. It is a four-point smoothing function based on spline functions (Breeuwsma catmull-rom spline). Have a look at gen~.interpolation.maxpat in the examples/gen folder for a patch that shows how the various interp modes are implemented internally.
spline_interp will be proposed in the autocompletion list. Create an instance, open the help ballon to get some help, click into the i to open the "gen~ Operators" page with a spline_interp reference in the Filter section (with the same smallish content).