This issue can be closed. It has been resolved as of statistics latest release.

I believe the nanmin and nanmax functions were introduced because the base functions did not not support flexible nan handling.  even matlab's help entries discourage use of the functions [1] recommending min/max and the 'omitnan' flag instead. They added 'omitnan' functionality to many functions, but Octave has yet to implement that flag for most of its compiled functions. I think Andreas was just expressing a similar preference for octave's functions.

Two somewhat separate issues here:

1 - As markus pointed out, matlab does not support
[v, idx] = nanmax (X, Y)
Was this just unintentional function definition copy/paste? Nanmax is just a wrapper to max so that should always fail since there's no definition for that in max.  Whether or not it is expected, idx should be documented.

2 - Even without calling for idx, `nanmin([1,2,NaN, 3],[2,1,NaN, 2])` is calling min for a second output anyway. the logic sholud be changed so it only calls for a second output with (X) or (X, [], dim) formats.





[1] https://www.mathworks.com/help/stats/nanmax.html

Afaict, the issue is that `min(A,B)` doesn't return a second output argument if B is non-empty (same for `max`). I'm not sure what that second output argument should be set to in that case. So, I have no idea which change in core Octave would help. Could you please elaborate?

Also, the current behavior of `max` and `min` is compatible to Matlab R2024a:

>> [v,idx]=min(ones(1,4),zeros(1,4))
Error using min
Two output arguments are not supported for two input arrays.

CC'ing package maintainer.