how do I make the function stop showing output arguments if an invalid input is entered.

function [max_h,H_dist]= A09Prob3_baler_erastogi(initial_v,launch_angle)
if ~(initial_v>=9.5 & initial_v<=13.25) %initial velocity limitation [m/s]
    fprintf('Initial velocity input is invalid \n') 
end
if ~(launch_angle>=30 & launch_angle<=60) % angle limitation [deg]
    fprintf('Launch angle input is invalid \n')
end
t= (initial_v*sin(launch_angle))/g; % maximum time [s]
max_h= 1.25+(initial_v*sin(launch_angle)*t)-(0.5*g*t^2); % maximum height in m
H_dist= (initial_v*cos(launch_angle))*t; % horizontal distance in m
end

Answer 1

[Ameer Hamza]

You can use assert(): https://www.mathworks.com/help/matlab/ref/assert.html. Which will throw an error if invalid input is given

function [max_h,H_dist]= A09Prob3_baler_erastogi(initial_v,launch_angle)
    assert((initial_v>=9.5 & initial_v<=13.25), 'Initial velocity input is invalid')
    assert((launch_angle>=30 & launch_angle<=60), 'Launch angle input is invalid')

    t= (initial_v*sin(launch_angle))/g; % maximum time [s]
    max_h= 1.25+(initial_v*sin(launch_angle)*t)-(0.5*g*t^2); % maximum height in m
    H_dist= (initial_v*cos(launch_angle))*t; % horizontal distance in m
end

If you don't want to throw an error, then you can simply return, but in that case, you will need to provide values for output variables

function [max_h,H_dist]= A09Prob3_baler_erastogi(initial_v,launch_angle)
    max_h = 0;
    H_dist = 0;
    
    if ~(initial_v>=9.5 & initial_v<=13.25) %initial velocity limitation [m/s]
        fprintf('Initial velocity input is invalid \n');
        return
    end
    if ~(launch_angle>=30 & launch_angle<=60) % angle limitation [deg]
        fprintf('Launch angle input is invalid \n')
        return
    end

    t= (initial_v*sin(launch_angle))/g; % maximum time [s]
    max_h= 1.25+(initial_v*sin(launch_angle)*t)-(0.5*g*t^2); % maximum height in m
    H_dist= (initial_v*cos(launch_angle))*t; % horizontal distance in m
end