Conditionals in Pbind

Questions
1

Hello,

I am not able to solve this problem: \amp should be 0.04, when \freq is above 300. And it should be 0.02, when freq is over 600:

(6.collect{|i|

	Pbind(
		\amp, 0.1,
		\scale, ~erv,
		\instrument,\sawy,
		\freq, Pseq([200,350, 500, 700],1),
		\amp, Pfunc{|e| if (e[\freq] > 300, {0.04}, {0.1})}, Pfunc{|e| if (e[\freq] > 600, {0.02}, {0.1})},
		\atk, 1,
		\dcy, 1,
		\dur,Pswitch1([Rest(1),1, Pseq([0.5, 0.5],1)],Pseq(~vl[i],1)),

).play(c)})

Any help would be appreciated!

2

Reformatting your \amp expression for readability:

Pfunc { |e|
	if (e[\freq] > 300) {
		0.04
	} {
		0.1
	}
}, Pfunc{|e| if (e[\freq] > 600, {0.02}, {0.1})},

… so the > 600 branch is entirely outside of Pfunc, so it’s not part of the conditional at all.

If you want to use if-then-else syntax, then second condition needs to be inside one of the outer if {} functions.

Perhaps a matter of taste, but I prefer to perform the most restrictive test first. You’re asking > 300 first, which, if true, then requires a second test > 600. But you could do > 600 first:

if (e[\freq] > 600) {
	0.02
} {
	if(e[\freq] > 300) {
		0.04  // <= 600, but > 300
	} {
		0.1  // <= 300
	}
}

case may be neater-looking than nested ifs – this is equivalent to if-then-elseif-then-elseif... in other languages.

case
{ e[\freq] > 600 } { 0.02 }
{ e[\freq] > 300 } { 0.04 }
{ 0.1 }

hjh

1 Like
3

In case you hadn’t considered these, here are some alternatives that do something similar…

You could consider this a relationship, such that when the pitch is high, the amplitude is low. Done here with Pkey and linlin.

Pbind(
	\dur, 1,
	\freq, Pseq([200, 350, 500, 700], 1),
	\amp, Pkey(\freq).linlin(300, 600, 0.1, 0.02, \minmax), // note the clip mode
).trace.play

If you explicitly want to map to each frequency to some state, rather that write a Pfunc for each case you could do it once, assigning an index to each state.

Pbind(
	\dur, 1,
	\freq, Pseq([200, 350, 500, 700], 1),
	\index, Pfunc({|e| 
		case
		{ e[\freq] <= 300 } { 0 }
		{ e[\freq] <= 600 } { 1 }
		{ 2 } 
	}),
	\amp, Pindex([0.1, 0.02, 0.04], Pkey(\index))
).trace.play
1 Like
4

Thank you so much for your help. case may be the most elegant solution here, you are right, it is neater-looking and more quickly to understand than the nested ifs. Thank you!

5

Jordan, thank you for your help. You are perfectly right, I was trying to have this kind of relationship when the pitch is high, the amplitude is low. Great, thank you so much, there is (obviously) so much to learn.

6

Are you trying to do amplitude key tracking to make higher fundamentals less piercing? I prefer to do that in the SynthDef rather than the sequencer:

sig = sig * freq.explin(1000, 2000, 0, -10).dbamp;

This creates a nice gentle slope where the amplitude is unchanged up to 1kHz, and then gently drops by -10 dB from 1kHz to 2kHz.

2 Likes
7

Nathan, That’s a nice way to do this, thank you for your advice!