[R] Fractals with R

Atte Tenkanen attenka at utu.fi
Wed Apr 18 21:20:11 CEST 2007

```Here is a workable version for the Julia set. I put it also to http://fractalswithr.blogspot.com/

Atte

> Now problems with plot-command...
>
> I try to plot Julia set and the algorithm works, if the points are
> drawn during the loop. But if I want to save the values first to
> the matrix and then afterwards plot them at once, the picture is
> distorted. What's wrong with the plot-command? I think the
> PointsMatrix is ok?
>
> -Atte
>
> C=-0.7-0.4i # Complex parameter, connected to coordinate of the
> Mandelbrot set in a complex plane.
> Limits=c(-2,2)
> z=0+0i
> MaxIter=60
> cl=colours()
> Step=seq(Limits[1],Limits[2],by=0.01)
> PointsMatrix=array(0,dim=c(length(Step)*length(Step),3))
> a1=0
>
> for(x in Step)
> {
> 	for(y in Step)
> 	{
>        	z1=x+y*1i
>        	n=0
>        	z=z1
>        	while(n<MaxIter & abs(z)<2)
>        	{
>                	z=z^2+C
>                	n=n+1
>        	}
>        	if(abs(z)<2) colour=1
>        	else colour=n*10
>        	#points(z1, pch=".", col=cl[colour]) # This works!
>
>               # But this doesn't!
>                a1=a1+1
>                PointsMatrix[a1,]=c(x,y,colour)
> 	}
> }
>
> #???
> plot(PointsMatrix[,1], PointsMatrix[,2], xlim=Limits, ylim=Limits,
> col=cl[PointsMatrix[,3]], pch=".")
>
> #-------------------------------------------------------------------
> ---------------------------------------------#
>
>
> > Atte Tenkanen wrote:
> > > Hi,
> > >
> > > That is of counter for web page. Do you get some pop-up windows?
> > >
> > >
> > > Atte
> >
> > Hi Atte,
> >
>
>

```