# For loop circles that wrap around another circle

6 views (last 30 days)
pauli relanderi on 14 Oct 2021
Commented: pauli relanderi on 15 Oct 2021
So my problem is that i need to plot circles that wrap around another circle.
The calculations calculate the R(inner circles radius) based on n(the number of circles that wrap around it and r which is always 1)
something like this :
i need to make an for loop k=1:n, that plots the small circles around the red inner circle.
ive tried everything and cant seem to get it right.
here is the base calculation ive gotten so far.
n=17 %number of small crircles
alfa=180./n %angle
x0=0,y0=0%circle center points
R=((1-sind(alfa))/sind(alfa))*r %calculating the R(radius of red inner circle)
%innercircle coords
t=0:360;
xymp=+R.*cosd(t);
yymp=y0+R.*sind(t);
%outer circle coords
t=0:360;
Syy=+(R+(r.*2))*cosd(t);
Syx=y0+(R+(r.*2))*sind(t);
plot(xymp,yymp,'r','linewidth',2)%inner circle
hold
plot(Syx,Syy,'b','linewidth',2) %outer circle
this is the for loop ive tried,
for k=1:n
s=0:alfa:360
x=x0+(R+r).*cosd(s)
y=y0+(R+r).*sind(s)
xy=x+r.*cosd(s);
yy=y+r.*sind(s);
plot(x,y)
end
i know its not pretty
Thanks for any help !

Mitchell Thurston on 14 Oct 2021
Modified the calculation of alfa, R, and a slight change with the for loop
clear;
n=17; %number of small crircles
alfa=180-(180*(n-2))/n; %angle
x0=0;y0=0;%circle center points
R=r*(1/(sind(180/n)) -1); %calculating the R(radius of red inner circle)
%innercircle coords
t=0:360;
xymp=x0+R.*cosd(t);
yymp=y0+R.*sind(t);
%outer circle coords
t=0:360;
Syy=+(R+(r.*2))*cosd(t);
Syx=y0+(R+(r.*2))*sind(t);
plot(xymp,yymp,'r','linewidth',2)%inner circle
hold on
plot(Syx,Syy,'b','linewidth',2) %outer circle
s=0:alfa:360;
for k=1:n
x=x0+(R+r).*cosd(s(k));
y=y0+(R+r).*sind(s(k));
xy=x+r.*cosd(t);
yy=y+r.*sind(t);
plot(xy,yy,'-k')
end
hold off
pauli relanderi on 15 Oct 2021
Love it ! Thank you !!

R2021a

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