How do I convert this integral equation to matlab code?

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.

Answer 1

[Torsten]

Use trapz instead of integral.

Best wishes

Torsten.