mattyo

I am perhaps an incredible idiot, and am overlooking something 

obvious, but I'm getting a rather odd response from some of the math 

objects. I have a simple patch to scale the file position output of 

sfplay~ to 0.-1. for window driving purposes. Offset and multiply, 

the scaler's mantra. Well, dividing by 1000. works fine, but, 

multiplying by .001 generates crazy numbers. Sitting on my mother's 

knee, she told me that dividing by 1000. was the same as multiplying 

by 0.001, but something seems a bit of here. I assume I'm whacking a 

limit on the number size, but why with mult & not divide? If I throw 

it together in straight max, btw,either of them work fine.

I am perhaps an incredible idiot, and am overlooking something  
obvious, but I'm getting a rather odd response from some of the math  
objects.  I have a simple patch to scale the file position output of  
sfplay~ to 0.-1. for window driving purposes.  Offset and multiply,  
the scaler's mantra.  Well, dividing by 1000. works fine, but,  
multiplying by .001 generates crazy numbers.  Sitting on my mother's  
knee, she told me that dividing by 1000. was the same as multiplying  
by 0.001, but something seems a bit of here.  I assume I'm whacking a  
limit on the number size, but why with mult & not divide?  If I throw  
it together in straight max, btw,either of them work fine.

multiplying-vs-dividing-in-audio-domain

in your patch you are not multiplying by 0.001 you are dividing by .001 this is mostly the cause of your confusion. Also you have the '2' message triggering 1000 into the - object on the left but on the right it's not connected. This will also mess you up.

1- your right-hand trigger is not plugged

2- your right-hand *~ is actually a /~...

1- your right-hand trigger is not plugged
2- your right-hand *~ is actually a /~...

Also note that your mother's knee assumed you were working with infinite precision decimal numbers.

Your computer is working with finite precision binary. There are some surprises in there. Google the list on, say 'floating-point precision' for numerous discussions. Peter Elsea has a helpful tutorial for a more structured explanation.

Also, the fine-print of the documentation for /~ points out that the object internally multiplies by the inverse when the divisor is constant. Your mother probably didn't tell you that floating point division is typically about 4-5 times more CPU load than mult.

Aside form the fact that I had not had enough coffee when I threw the 

example together, I was right in principle....

And my mother did tell me about the efficiency of mult vs. div - thus 

while I was trying to to use mult. Nice to know it's built in.....

On Feb 14, 2008, at 11:42, Peter Castine wrote:

> Also note that your mother's knee assumed you were working with 

> Your computer is working with finite precision binary. There are 

> some surprises in there. Google the list on, say 'floating-point 

> precision' for numerous discussions. Peter Elsea has a helpful 

> tutorial for a more structured explanation.

> Also, the fine-print of the documentation for /~ points out that the 

> object internally multiplies by the inverse when the divisor is 

> constant. Your mother probably didn't tell you that floating point 

> division is typically about 4-5 times more CPU load than mult.

Aside form the fact that I had not had enough coffee when I threw the  
example together, I was right  in principle....

And my mother did tell me about the efficiency of  mult vs. div - thus  
while I was trying to to use mult.  Nice to know it's built in.....

>
> Also note that your mother's knee assumed you were working with  
> infinite precision decimal numbers.
>
> Your computer is working with finite precision binary. There are  
> some surprises in there. Google the list on, say 'floating-point  
> precision' for numerous discussions. Peter Elsea has a helpful  
> tutorial for a more structured explanation.
>
> Also, the fine-print of the documentation for /~ points out that the  
> object internally multiplies by the inverse when the divisor is  
> constant. Your mother probably didn't tell you that floating point  
> division is typically about 4-5 times more CPU load than mult.
>
> -- P.
>
>
> --
> ----
> Peter Castine
> Litter Power: 
> iCE Tools: 
>


multiplying vs. dividing in audio domain