Gravitational Interaction Issue with 'busy' signal

I'm building some code for a gratiational interaction problem. My code doesnt work becuase im still learning how code in matalb. Im trying to model the interaction of a small object and a larger planet. Basically with an object(mass of it is insignificant and cancels out) with an intial velocity in the +y direction and then trying to graph the x and y position rotating it around the planet. Any help is appretiateed becuase it seems like I have an endless while function.

%Gravitational interaction
clc, clear
close all 

delta_t=.01;
G=6.67*10^-11;
M=input('Enter mass of plantet(kg): ');
R=input('Enter distance from planet(m): ');
v=input('Enter speed(m/s): ');
if (v<=0)
    disp('Illegal Input')
end
theta=0;
vx=v*cosd(theta);
vy=v*sind(theta);
vx(1)=0;
x(1)=0;

i=1;
while  min(R)> -.001
    a(i)=G*M/R(i).^2;
    vx(i+1)=vx(i)+(a(i)*delta_t);
    vy(i+1)=vy(i)+(a(i)*delta_t)
    x(i+1)=x(i)+vx(i)*delta_t+.5*a(i)*delta_t.^2;
    y(i+1)=y(i)+vy(i)*delta_t+.5*a(i)*delta_t.^2;
    R(i+1)=R(i)-x(i+1);
end

plot(R,v(i))