That's actually pretty simple: you can loop over all the y values and check whether there is a sign change between the current and the next value. The latter can be done for example by checking if y[n]*y[n+1] is <0. The condition is true for a sign change between elements with idices n and n+1. You then take n (or n+1) as the index for getting the time, i.e. x[n] of the zero crossing.

Andreas

Thanks for the quick response.  I think this method should do it. Thanks again!

Hi Andreas,

The simplest solution is to check the sign of the slope at the zero crossing, i.e. if (y[n+1]-y[n]) >0 then you've crossed from minus to plus.

Andreas

Thanks, will probably try this tomorrow.