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## Re: zero crossing determination in octave?

**From**: |
Carlo de Falco |

**Subject**: |
Re: zero crossing determination in octave? |

**Date**: |
Sat, 6 Dec 2008 08:34:06 +0000 |

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.
`c.