How to patch y[n] = x[n]/samplerate + y[n-1] with x the input and y the output in Pure Data?

Found out just now that the feedback of y by using [send] + [receive] to get y[n] = x[n]/samplerate + y[n-1] results in a drift of y that ultimately drowns the signal.

(x)
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[*~ inverse of samplerate]
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[rpole~ 1]

Thank you! Yes that should work, but strangely I'm not getting the results that I think I should get...

@Nobody what results do you think you should get? seems like you should get a kind of lowpassed triangle wave on the right side with that configuration.

I'm trying to make a mathematical integrator module (not a slew limiter), and indeed feeding a square wave should result in a triangle wave at the output. But sadly for some reason it's not working...

Now we are getting somewhere:

Is such a feedback loop as below forbidden in Pure Data? Can't get it to work...

Yes, it's forbidden. You can't loop signal objects like that. You have to use a [send~] / [receive~] pair to make the loop.

Thanks! Yes the loop is working now.

Is there a simple way to give a single pulse to startup the patch instead of the workaround in the red circle?

@Nobody said:

Is there a simple way to give a single pulse to startup the patch instead of the workaround in the red circle?

The best way I know is to create a two element array -- first value 1, second value 0 -- then tabplay~ to get the impulse.

[array define dirac]

[loadbang]
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[t b b]
|     |
|     [; dirac resize 2; dirac 0 1 0(  <<-- message, not object
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[tabplay~ dirac]

(From memory, maybe I got the array messages wrong)

hjh

Why isn't the patch below inverting the input signal?

@Nobody said:

Why isn't the patch below inverting the input signal?

If the -1 message isn't being transmitted, then *~ might not be multiplying by -1...?

Otherwise... what is it doing instead of inverting?

hjh

Thanks. I now have the following and it is working now.

Just put -1 as an argument, like this [*~ -1]

Ah - that's even better.