How to compute impulse and frequency response of Flanger? I have to the implementation of a Flanger effect on Matlab, buy previously I have to plot its frequency response and impulse response.

The difference equation is $y[n]=x[n]+a\cdot x[n-d[n]]$
where $a$ is a constant, $|a|&lt;1$, and $d[n]=\frac D2 (1-\cos(2\pi f_s n))$;
$D$ and $f \text{ const}$.

I'm having trouble on how to calculate any of DTFT o Z Transform of such difference equation. I can't find how to compute the varying time shifting transform for $x[n-d[n]]$.

Is there any other way to compute impulse and frequency responce?
Only linear time invariant systems are fully characterised by their impulse response. Modulation effects like a flanger break time invariance. While you can still create a momentary impulse response (which is only of very limited use), there is no meaningful frequency response.