Re: Please help quick!

*To*: mathgroup at smc.vnet.net*Subject*: [mg4613] Re: Please help quick!*From*: jlc <jade at darkwing.uoregon.edu>*Date*: Wed, 21 Aug 1996 03:25:30 -0400*Organization*: University of Oregon*Sender*: owner-wri-mathgroup at wolfram.com

On 7 Aug 1996, kirstin wrote: > I'm looking for a very simple program that makes spirographs. Preferably Mac, PC in worst case. Time is of the essence... does anyone have any info??? Thanks!!!!! > R[t_] := {{Cos[t],-Sin[t]}, {Sin[t], Cos[t]}} Spirograph[t1_,t2_,p_]:= ParametricPlot[ Evaluate[{R[t].{t2-t1,0}+R[-(t2-t1)*t/t1].{p,0},R[t].{t2,0}}], {t,0,2*Denominator[(t2-t1)/t1]Pi}, PlotStyle->{{RGBColor[0,0,1]},{RGBColor[1,0,0]}}, PlotPoints->12*Denominator[(t2-t1)/t1], AspectRatio->Automatic] t1 is the radius of the inner circle, t2 is the radius of the outer one and p is the distance of the pen from the center of the inner circle, of course unlike a real spirograph its possible to make the inner circle bigger than the outer. The modification that has the smaller circle rotating around the outside of the inner one is fairly simple. You should really thank George Mcninch for teaching me this bit of code. ~joshua is this machine recording? ==== [MESSAGE SEPARATOR] ====