How do I convert this integral equation to matlab code?

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John Doe
John Doe 2015-3-30
回答： Torsten 2015-3-30
I'm trying to write a matlab program for a Lock-in Amplifier, based on this equation:
where Fref is the frequency you're trying to extract, t the current time sample, T the total time, Fin the input signal and phi is the phase. Reference: http://en.wikipedia.org/wiki/Lock-in_amplifier
When it comes to the integration I'm stuck. My phase is 0, my time is 4.8828 seconds incrementing in 0.002 second steps per signal sample.
sigRef = 25;
mult = 2*pi*sigRef;
t=[0:1/512:4.8828];
Uin = trialDataL; % same length as t
fun = @(x) sin(mult*t(x)*Uin(x));
q = integral(fun,1,2)
"Integral" doesn't like using x as an index instead of a numeric value, but I don't know how to get t and Uin to both change samples at the same time.

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Torsten
Torsten 2015-3-30
Use trapz instead of integral.
Best wishes
Torsten.

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