How to find x data in a interpolate curve?

Hello everybody,

how can I find the data of x related to y on a curve interpolated data for x and y?

wanted to find the time for example regarding the flow accumulated 2867.04.

function

https://docs.google.com/file/d/0B9JmyPHF_ZMPMmtGV3hNMnpkUjg/edit?usp=sharing

date

https://docs.google.com/file/d/0B9JmyPHF_ZMPTzdlUHlibjFzRzg/edit?usp=sharing

Answer 1

[Andrei Bobrov]

f2 = @(y)fzero(@(x)fitresult(x)-y,0);
out = f2(2867.04);

[Artur M. G. Lourenço]

thanks