zero crossing determination in octave?

[J. Patrick Bedell]

Hello again,
   Just to clarify, I am asking about estimating the zero crossings of
a waveform specified as (x,y) values, not finding the roots of a
polynomial or other function.
   Thanks!

   Patrick

On Fri, Dec 5, 2008 at 12:07 PM, J. Patrick Bedell <jpbedell at mises.com> wrote:
> Hello,
>   Is there an octave function to compute (possibly using
> interpolation) the points at which a given waveform crosses the x-axis
> (or a specified threshold value)?
>   Thanks!
>
>   Patrick
>