i get the message: "expr~ divide by zero detected" in the console when i do something when dsp is on, when i turn on dsp, or when i take th right inlet of expr~ and set it to 1 with my vertical slider that goes fram 0 to 1 on this-patch.pd. i have checked the code by thinking about all the different scenarios where it would divide by zero, but i found none. in addition to all of that, it works just fine even with that error.

can somebody check my code to tell me why it says that?

@4ZZ4 last part........ /(1-$v2)......... when $v2=1......
Try [clip 0 0.999]
David.

@whale-av no, because my if statement contains ($v2==0||$v2==1, some replacement for dividing by zero, the operation containing /(1-$v2))

this means when $v2=1 it would do another operation (see the patch), and the same for $v2=0.

still, why is that error there?

I think it's just an interpreter warning, not a runtime error. If you try [expr~ if ($v1<42, 1, 1/0)} you get the same warning, whereas [expr~ if (1==1, 1, 1/0)] you don't.

I've never seen PD throw a division-by-zero runtime exception. I think it just silently substitutes some number and doesn't worry about it. If I'm right, then think of the warning as "is that what you really meant?" Check this out:

Not even a warning.

@jameslo Thank you

BTW, it's hard to figure out what a thicket of nested if-then-else clauses does, maybe even for you if you find yourself modifying this patch a year from now. Here's another way to create a variable duty-cycle triangle oscillator that I find a little clearer:

Returning to the divide-by-zero discussion, try bypassing the clip.
vdc tri.pd

@4ZZ4 [expr if........] and [expr~ if.........] calculate both the true and the false parts...... but of course only one of them is returned.
"If always evaluates both truepart and falsepart, even though it returns only one of them. Because of this, you should watch for undesirable side effects. For example, if evaluating falsepart results in a division by zero error, an error occurs even if expr is True."
Which is why I posted as above......
David.

@whale-av you have great knowledge, but why would it calculate both? it seems like a stupid feature... it does not do anything. is it to keep the code "stupidly simple" (KISS)?