# [PD] signal math explanation

Jonathan Wilkes jancsika at yahoo.com
Sat Jan 18 20:32:12 CET 2014

```Hi Pall,
Which help patches?  I haven't seen a single help patch that substitutes strings of [+~] to double the incoming signal where a simple multiplication would do.

I have seen cascades of [+~] for additive synthesis, but that's not the same.

-Jonathan

On Saturday, January 18, 2014 1:00 PM, Pall Thayer <pallthay at gmail.com> wrote:

Ah... I've seen this in some of the help patches. Why would someone do it with multiple [+~] instead of a single [*~]? There's no difference?

On Sat, Jan 18, 2014 at 12:49 PM, IOhannes m zmölnig <zmoelnig at iem.at> wrote:

On 01/18/2014 06:24 PM, Pall Thayer wrote:
>> Can anyone tell me what one is accomplishing when doing something like this:
>>
>> [osc~ 440]
>> |
>> [+~]
>> |\     x1
>> [+~]
>> |\     x2
>> [+~]
>> |\     x3
>> [+~]
>>        x4
>
>>
>> In other words, the chain of [+~] that feed the previous object's output
>> into both inlets of the next... what does this do exactly?
>
>it adds a signal with itself: y=x+x=2*x
>
>so the output of the 1st [+~] is
>x1=x0 (as the 2nd inlet~ is not connected)
>and the following [+~] will output:
>x2=x1+x1=2*x1=2*x0
>x3=x2+x2=2*x2=2*2*x0=4*x0
>x4=x3+x3=2*x3=2*4*x0=8*x0
>
>so you could write the patch as:
>
>[osc~ 440]
>|
>[*~ 8]
>
>
>more often you see [*~] instead of [+~], which is a simple way to square
>the input.
>
>IOhannes
>
>
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