Does any one know what function it might serve ?

(sqrt~: squre root)

Thanks.

]]>i’ve been implementing it in max as such but don’t know if its as simple as that

thoughts anyone?

]]>similar methods are described elsewhere and this sounds like a more complex approach than just dividing 1 by the output of the in-built sqrt object’s output… or is it.

anyone elses thoughts?

]]>This is a math call common in programming libraries that saves processing power in tasks where the increased accuracy is not needed. Implementing 1 / sqrt(x) is fine as a replacement, and there is *probably* no need to worry on a modern processor about the speed.

]]>[expr~ 1./srqt($f12)]

only one object and more accurate.

-110

]]>Looking at the the source code for rsqrt~ in pd (in d_math.c) it looks as though its based on this algorithm

http://en.wikipedia.org/wiki/Fast_inverse_square_root#Overview_of_the_code

which makes sense given it’s description in the pd docs but looks like it would need a c external to implement in max.

]]>well there is a lot of code on the wikipedia site. :)

one of them is what i suggested:

http://upload.wikimedia.org/math/b/b/5/bb56561eddeafb2a43230a9a91d10d5e.png

edit:

i have no idea how to read that c code.

but implemeting an “only if input is greater than 1 for the sqrt argument seems a good idea.

in expr we could let it output 0 as result when the user is so stupid and asks for the 0.7th square root:

[expr~ (1./srqt($f1$f2))*($f2>1)]

]]>i’m using it for some of the fft bin operations in settel and lippe’s papers – anyone else doing something similar?

]]>more CPU than the clever method found in rsqrt.

and actually it seems like a joke that rsqrt is available to pd users but not with jitter,

where a recip. sqrt is probably more used than in audio or logic programming.

edit (bad manner, i know):

i have no idea, is the audio expr~ coming with maxmsp now? and is it available for

windows?

you might better stay with the math objects and ignore my above expr.^^