superformula

Code:

  function sf2d(n,a)
    u=[0:.001:2*pi];
    raux=abs(1/a(1).*abs(cos(n(1)*u/4))).^n(3)+abs(1/a(2).*abs(sin(n(1)*u/4))).^n(4);
    r=abs(raux).^(-1/n(2));
    x=r.*cos(u);
    y=r.*sin(u);
    plot(x,y);
  end

can anyone divine a translation of this superformula algorithm into reaktor? on the surface it looks pretty simple and I wonder what kind of applications it could have.
http://en.wikipedia.org/wiki/Superformula

 

what does the inner parentheses mean? (cos(t)) i imagine that to be cos merged with m*u/4 or cos replacing m: cos*u/4

 

is this ^ a xor?

i don't understand this line "Also note that x^(-1/n) = 1/x^(1/n) and x^(1/n) is the nth root of x." so i'm afraid i'm misunderstanding everything else too

 

^ is a commonly used symbol in math notation.

x^y means raise x to yth power. ie 2^4 = 2*2*2*2 = 16

i suggest you use primary to do this math, the x^y modules in core are finicky.

 

thanks guys. how far off am i? i don't see where n4 goes

 

i'm a bit lost in the details at this point. my solution seems to create a broken circle.

 

beautiful little code block. thanks again! hope this thread continues to educate

 

?

 

you could also get a cosine out of a sine wave by offsetting the phase (not that it's necessary as herw pointed out).

 

jim, the sine/cosine module in primary is normalized to have an input from -1 to 1 instead of the usual -pi to pi, that's what's causing errors. divide the input by pi and it should work.

i imagine this is to simplify making a sine wave out of the ramp oscillator and such tasks, but can be confusing for math.

 

yes - and an intersting point is, that there is no analogue equivalent, so it is really digital sound design.
Ciao herw

 

how do you get the difference?

with modulation on all the parameters and xy fade up to 99 you can get some decent approximations of psychedelic geometry

 

Could you elaborate on this ?.
I created a chebby shev shaper in core
The firt 12 polynominals ...full of pow's ....no problem whatsoever .

 

well sure. there's the obvious problem of x needing to be positive in core.

further you can see one of the problems by raising .0001 to the 30th power, which gives you a value of 0 in primary (as it should) and a value of 1.34*10^34 in core.

mind you, this is rarely important, but good to keep in mind if you are getting into deep math.