Do you know a VI to detect numerical zeros in a graph?

[seguy_laurent]

I need to detect numerical zeros in a graph and I don't know the analytical formula of the function represented on the graph.

[Mads]

If you just want to detect zeros in the array that represents the graph just search the array for zeroes...However if you want to detect zero crossings you can do it as described here:

http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=5065000000080000008B2B0000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0&USEARCHCONTEXT_QUESTION_0=Zero+crossing&USEARCHCONTEXT_QUESTION_S=0

A similar example can be found on:
http://sine.ni.com/apps/we/niepd_web_display.DISPLAY_EPD4?p_guid=B123AE0CB8F6111EE034080020E74861&p_node=DZ52028&p_submitted=N&p_rank=&p_answer=&p_source=External

Or if it fits you task; use the in-build zero crossing point by point detector that comes with LabVIEW...

If you do it by detecting changes in sign you can interpolate
between the two points to find the exact position of the crossing. Attached is an example that does just that.