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# finding the time of when 2 variable intersect (cis capture)

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#### nlight

##### Newbie
OK so basically I have vg (which is constant) and vc (which is a variable of a function) I can go into the graph after simulation and see what time stamp they intersect in and devide that value by 3600 to find TG but I need a way calculate it automatically

I tried using ABM2 component to do if(v(g)=v(c),v(t)/3600,0) but it didn't work plus even if this worked the out come will be 0 untill it reaches TG any help?

This seems like it's a matter of solving simultaneous equations. Is that what you have?
The method is possible if they are linear, that is, straight lines on a graph. That has at most one intersection.

OTOH it gets complicated if a curve is in the mix. Such equations may result in more than one intersection.

Is your graph a curve? There are computer programs which examine a graph and then generate the formula which produces it.

One is linear constant function the other is a curve

I tried to make an if expression between vc and vg like I mentioned previously but didn't work so I removed it
here is the circuit

are your two values, vc and vg, always as in the simulation?
that is, does vc always start less than vg and increase in an exponential(?) manner?
this implies there is only one solution

apparently you have an equation next to each of the blocks in your schematic
given whatever inputs you have, do you know the net equation for vc?

it may not be easy, but you should be able to solve constant = function of time
one way to get a symbolic solution is to use wolfram alpha
type in your equation, vc = f(t)
tell wolfram alpha to solve for t

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