zero crossing determination in octave?

[Jack Crenshaw]

Carlo de Falco wrote:
>
> On 06/dic/08, at 01:08, Jack Crenshaw wrote:
>
>> Um ... I think Patrick was looking for a function that would iterate 
>> on the solution. In Matlab, that's fzero.  Your function is only a 
>> linear approximation, which might be Ok if the data array is dense, 
>> but otherwise, NG.
>>
>> Jack
>
> Jack,
> If the "waveform" is given as data samples (x,y) as specified in 
> Patrick's post:
>
> On 05/dic/08, at 20:15, J. Patrick Bedell wrote:
>>  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
>
>
> this is the best you can get.
> To use fzero you would need to hava a function to compute y(x) for any 
> given x (and an initial guess).
> A possible improvement could be to use a smoother interpolant but that 
> only makes sense if you know a-priori that the samples come from a 
> smooth function.

Ok, I see your point. Sorry for jumping to conclusions.

Jack