[Csnd] Manual example for lfo, question/error

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1

Hi,

I stumbled upon this while marking student assignments. I wanted to double check the manual for the lfo opcode. So I also checked the example (example 500 Advanced example of the lfo opcode).
The delay time for vdelay will be modulated in strange ways, as kAmpDELAY1 goes negative:

kAmpDELAY1 lfo, 100, 1.35, 1 kAmpDELAY1 = kAmpDELAY1 + 50 ; DELAY SIGNAL adel1 vdelay asig1, kAmpDELAY1, 500

not sure what to do about it but thought I’d let someone know :wink:
Øyvind

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2

The code in question is:

        buf[indx] = in[nn];
        fv1 = indx - fdel * esr;
        /* Make sure inside the buffer */
        /*
         * See comment above--same fix applied here. heh 981101
         */
        while (UNLIKELY(fv1 < FL(0.0)))
          fv1 += (MYFLT)maxd;
        while (UNLIKELY(fv1 >= (MYFLT)maxd))
          fv1 -= (MYFLT)maxd;

and fdel is the delay time input. There is no check to make sure it's non-negative,
so there’s a wraparound. Not the right thing in my book, but I didn’t write it.
As usual, we can’t change it.

I don’t think it is documented. Maybe one for the manual issues.

3

Thanks for the clarification re vdelay, but what I intended to say is that the advanced manual example for lfo should perhaps be changed, so it generates valid delay times(?)

It says ; By Stefano Cucchi 2020

Maybe if Stefano is here, he would chime in.
all best
Øyvind

4

That and perhaps saying for vdelay that delaytime is modulo max delay.

Prof. Victor Lazzarini
Maynooth University
Ireland

5

As I recall from books by Julius Smith, that there is
a difference between fdelay and vdelay.

-Partev

That and perhaps saying for vdelay that delaytime is modulo max delay.

Prof. Victor Lazzarini
Maynooth University
Ireland

6

While looking this up in the manual, came across a spelling error
while in the “f” opcodes.

faustaudio — Instantiates and runs a compiled Faust program.

[faustdsp](https://csound.com/docs/manual/faustdsp.html) — Instantiates a Faust program.
I don't think it's instantaneous, so I'm guessing "*initiates*".
Could be confusing, did a double-take myself, thought I'd
give a heads up on that.
-Partev

As I recall from books by Julius Smith, that there is
a difference between fdelay and vdelay.

-Partev

That and perhaps saying for vdelay that delaytime is modulo max delay.

Prof. Victor Lazzarini
Maynooth University
Ireland

7

No, it’s instantiate alright. Puts an instance of the program in memory.

Prof. Victor Lazzarini
Maynooth University
Ireland

8

EmojiOh, interesting. Not familiar with that term. Okay then.
Hmmm,…
Thanks. Hmmm,…

-Partev

No, it’s instantiate alright. Puts an instance of the program in memory.

Prof. Victor Lazzarini
Maynooth University
Ireland

9

It’s a very common term in object-oriented programming.

Prof. Victor Lazzarini
Maynooth University
Ireland

10

Aahh,… should’ve known. Don’t do much of that.
That explains it.

Thanks.
-Partev

It’s a very common term in object-oriented programming.

Prof. Victor Lazzarini
Maynooth University
Ireland