Diameter of a Cyclotron

%% Diameter of a Cyclotron
% Determines the diameter of ions in a cyclotron and how many times the
% ions complete their orbit in a given amount of time.

% Constants
elemCharge = 1.6*10^-19;             %[C] Elementary Charge

% Inputs and Variables
q = input('Are the ions singly, doubly, or triply charged?\n')*elemCharge;
B = input('What is the magnetic field?\n');
mass = input('What is the mass of the ions in kg?\n');
v = input('What is the speed\n');
t = input('How many seconds?\n');

% Ouputs and Equations
r = mass*v/(q*B);
d = 2*r;
c = pi*d;
orbits = v*t/c;
fprintf('The diameter is %.3f m and the ions make %.4e revolutions', d, orbits);