Energy to Accelerate a Spaceship

%% Energy to Acclerate a Spaceship to Relativistic Speed
% Determines the energy required to accelerate a spaceship and how many
% missions are possible in a year

% Constants
c = 3.00*10^8;                  % [m/s] Speed of Light

% Inputs and Variables
M0 = input('Mass of spaceship\n');
Beta = input('Speed of spaceship without c\n');
K = input('Energy from the sun\n');
eff = input('Efficiency in percent\n')*10^-2;

% Outputs and Equations
Work = M0*c^2*((1/sqrt(1-Beta^2))-1);
missions = K*365*eff/Work;
missions = floor(missions);
fprintf('Energy required: %.3e J\nMissions: %f\n', Work, missions)