[PD-dev] Creating an external / sinewave equation example

[Rick T]

Greetings All

I'm having trouble getting my external to work, It compiles with 5 warnings
sineq.c:48: warning: unused variable ‘x’
sineq.c:49: warning: unused variable ‘in1’
sineq.c:50: warning: unused variable ‘in2’
sineq.c:51: warning: unused variable ‘in3’
sineq.c:52: warning: unused variable ‘in4’

It does a "make" successfully but I get this warning message
/usr/bin/ld: warning: cannot find entry symbol xport_dynamic; defaulting to
00000000000007f0

but when I try and add it in PD it says "couldn't create".  I've looked at
the pan~ tutorial and the d_osc.c file as recommended, which did help.  I
tried to take pieces from the two which I thought were applicable to my
situation but I'm still having some issues.

Here's a link to the workflow (dropbox)
http://dl.dropbox.com/u/6576402/questions/pd/Sine_EQ_Diagram.jpg

Here's a link to the C code online (pastebin)
http://pastebin.com/9rK3szUE


My external is a reproduction of the sinewave equation with 4 inputs and one
output my logic is to have 4 inlets one for the frequency,amplitude,phase
and vertical offset and an output for the created signal.  Granted this
isn't the final equation but this will help me understand how to create the
full equation once done.   If you want to see the full equation I'll be
using here's a link to it below.  Basically it's a 1 second periodic signal
with the sample rate at 44100 which the equation gives me control over the
frequency,amplitude,phase and vertical offset, which will be controlled by a
usb midi controller.

Another question I have is what do I use for the t (time) for my final
equation is that the t_sample object in PD?  or do I need to create a for
loop counting from 1-44100 for a 1 second 44100 sampled equation?

http://dl.dropbox.com/u/6576402/questions/eq1.txt

PS: I'm compiling on ubuntu 10.04 using gcc

On Sun, Sep 4, 2011 at 12:13 PM, Martin Peach <martin.peach at sympatico.ca>wrote:

> On 2011-09-04 16:52, Rick T wrote:
> ...
>
>
>  I've been able to find instructions on how to create a hello world
>> C-external but not one that creates a simple sine wave from a sinewave
>> equation like A*sin(w*t+p)
>> (https://secure.wikimedia.org/**wikipedia/en/wiki/Sine_wave<https://secure.wikimedia.org/wikipedia/en/wiki/Sine_wave>)
>> Does anyone
>> have one or know where to find one.
>>
>
> The canonical reference is here:
> http://iem.at/pd/externals-**HOWTO/node6.html<http://iem.at/pd/externals-HOWTO/node6.html>
> You just need to plug your equation into the perform routine.
> Also check the source for osc~ in d_osc.c of the Pd source, which uses a
> fancy 32-bit float cosine table scanning method that was useful when it
> mattered but is getting obsolete as a call to sin() is probably just as fast
> nowadays.
>
> Martin
>
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