I am reading about reverb algorithms and I came across the concept of nested allpass filters.

Here's an illustration of a regular allpass filter:

And here's a nested allpass structure:

source: http://gdsp.hf.ntnu.no/lessons/6/33/

I used those illustrations as well as H14.all.pass from the audio examples as the basis. But I am not sure I am doing this right at all....

Here's a vanilla allpass I made:
vanilla_allpass~.pd

And here's a nested allpass using the above abstraction:
nested_allpass~.pd

Is this a proper nested allpass? If not, where am I going wrong? As you might guess, I don't fully understand [rzero_rev~] and [rpole~].
Cheers

I got it to work!
I thought I might try compiling from source after all, so I installed CMake and Visual Studio. In Visual Studio, I only installed "C++ CMake Tools for Windows" and the latest Windows 10 SDK. Then I just wanted to check something quickly in pd before getting into compiling, but it seems that one of these installations already fixed the problem and I am running csound now from within pd. Can create the object and all works as it should. But I only opened pd again after hours of installing, tinkering with, and uninstalling things, so I can't tell exactly what it was that fixed it for me now.

@jameslo Thanks, I've tried it, but no luck unfortunately. Pure Data console says:

tried C:/Users/IceIce/AppData/Roaming/Pd/csound6~/csound6~.dll and succeeded
C:\Users\IceIce\AppData\Roaming\Pd\csound6~\csound6~.dll: The specified module could not be found.
 (126)

and further down:

csound6~: can't load library

But it's there, csound6~.dll is in that folder. It's strange that it succeeds, but then it says that it can't be found. Also, I was surprised to see that csound wasn't on deken. EIther way, I am on a 64-bit system, and I am not sure if the download is 32-bit. Does it run for you? What steps did you take? Thanks in advance.

I want to play with Csound from Pure Data. Csound is installed and I can run Csound things from the command line just fine. I downloaded csound_pd from this link:
https://github.com/csound/csound_pd/releases
Extracted this to my externals folder and added the directory to Pure Data's Path.
But I can't create any instances of [csound6~].
Are there any further steps required to get it to run?
I don't know if I have to build it myself (never done this before). But there is a csound6~.dll in the externals folder, so I suppose I don't have to build this...

Tried it and it works. Head conversion works, too. Cheers!

@whale-av
Wow, thanks a bunch! Yes, it's the "struct color" as in your patch pd-colours.pd. This is a really helpful index. Finally, I know where all these nice yellows and oranges are. Cool that you added the list of tcl colours as a txt, I saw that yesterday in the tcl/tk documentation.
H̶o̶w̶e̶v̶e̶r̶,̶ ̶I̶ ̶c̶a̶n̶'̶t̶ ̶c̶r̶e̶a̶t̶e̶ ̶[̶s̶y̶s̶_̶g̶u̶i̶]̶ ̶o̶r̶ ̶[̶c̶o̶l̶o̶r̶p̶a̶n̶e̶l̶]̶.̶ ̶A̶r̶e̶ ̶t̶h̶e̶s̶e̶ ̶e̶x̶t̶e̶r̶n̶a̶l̶s̶?̶
They're in hcs, which I had installed already. Having a blast right now making my own pd theme!!

@oid
Oh nice! But sending hex values gives me "argument number out of range", anything I am missing here? I tried any formatting, like #AAAA77, #aaaa77, AAAA77, and aaaa77. But none of these worked. Also tried it as symbols, by message or through [symbol], but to no avail.

Changing colour of all the other GUI objects is straightforward:
Sending an int will cycle through the 30 preset colours in the Properties dialog.
But what about arrays? Sending an int to an array via [color $1] seems to cycle through an enormous list of subtle shades.
See the screenshot where I am sending the same value to all the GUI objects. The colours are obviously not the same.

What are the values? Is this list buried somewhere in the pd files?
I have been wondering for years, but I'm done guessing now

@seb-harmonik.ar
Wow, thanks a lot! A very interesting patch, going through this one step by step has taught me a lot.
And very true what you said about the purpose and use of [expr]. I see now that I used to look at the object as something completely different than it's actual purpose.

I am sitting with a little patch here... I want to calculate the digit sum of an integer.
What I have so far works with any integer up to and including 99. But the trouble starts at n >= 100.
See the patch attached: DigitSum.pd

I got this working in Python, for any integers:

def digSum(n):
 
    out = 0
    while (n != 0):
        out = out + int(n % 10)
        n = int(n/10)

    return out

for x in range(1,200):
    n = x
    print(n, ":", digSum(n))

But [expr] seems to not do while-loops, unless I am mistaken?
I have tried sloppy workarounds, chaining up multiple [expr} objects, but it's error-prone, ugly, and convoluted.
The end goal is to be able store the digit sums of a given range of integers in an array; Like you can see in the right-hand section of the DigitSum.pd patch.

Anything I am missing here?

Hi there!
Great vid, and nice sound, too! Kinda bagpipey, I really like it!
I am sitting with a very similar project at the moment: Interpolating between arrays, writing the results of the interpolation to another array, which serves as a wavetable. I have tried different approaches, using [expr] turned out to be the most malleable one. What object are you using for your calculation there?