Re: [Octave-bug-tracker] [bug #36732] interp1 does not check input for monotonicity

[Francesco Potortì]

>About non-distinct points, I am assuming that the
>Manual is correct. It says in Section 29.1:
>
>Duplicate points in x specify a discontinuous interpolant. There should
>be at most 2 consecutive points with the same value.

Most probably, this means that, once the X are sorted, any repeated
points should be in couples (i.e. three consecutive repeated points are
not allowed), but there is no limit on the number of couples.

>The discontinuous interpolant is rightcontinuous if x is increasing,
>left-continuous if it is decreasing. Discontinuities are (currently)
>only allowed for "nearest" and "linear" methods; in all other cases, x
>must be strictly monotonic.

This makes little sense, because X is sorted in increasing order anyway.
Maybe this was a comment written at a time when there was no sorting in
place.

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