Why do I receive Warning: Marker input is ignored?

This is the code for simulating a 'pulse-and-glide' car journey:

clc
clearvars

% Aero constants Faero = 0.5*rho*Cd*Af*v^2
Cd = 0.37;
Af = 1.52;
rho = 1.225;
 
% % Rolling resistance ceofficient (Frr = Normalforce*Crr)
Crr = 0.00294;

% Vehicle/earth constants
mveh = 80;
mload = 40;
m = mveh+mload;
g = 9.81;

% Distance of PNG section, 1 mile in metres
intervallength=1609;

% Velocity thresholds m/s
vlow = 3.1;
vhigh = 5.5;

Tm = 1.5; % Torque generated by the motor
GR = 8; % Gear Ratio
% Think about how you calculate Tw and Ft. Note gear ratio is a
% *reducation* ratio. Motor speed is faster than wheel speed... so what
% happens to the torque?
Tw = GR*Tm; % Torque at the wheels
% Tw is equal to GR*Tm
rw = 0.4; % wheel radius
% Assuming that the rolling radius of the wheel is the same as the radius
% of the wheel, the intuition being the tyre is filled up with
% incompressible fluid
Ft = Tw/rw; % Tractive Force

% At time equals zero, vehicle will accelerate from standstill. 
pulseflag = 1; % When vehicle pulsing, pulseflag is 1. When coasting, pulseflag is 0

% Initialise displacement, velocity and acceleration
x(1) = 0;
v(1) = 1e-10;
a(1) = 0;

% Timestep
dt = 0.1;

% Define values that are constant
normalforce = m*g; % Normalforce 
Frr = Crr*normalforce; % Rolling resistance 

% Iniitalise counter
k = 1;

while x(k)<=intervallength % while loop
    % Define values that change every iteration
    Faero(k) = 0.5*rho*Cd*Af*v(k)^2;
    Fd(k) = Faero(k) + Frr;

    % Are we pulsing, and what's the acceleration in the next loop?
    if pulseflag == 1
        a(k+1) = (Ft-(Faero(k)+Frr))/m;
    else
        a(k+1) = (-(Faero(k)+Frr))/m;
    end

    % What's the velocity in the next loop?
    v(k+1) = v(k)+a(k+1)*dt;

    % Setting pulseflag for next iteration
    if v(k+1) >= vhigh
        pulseflag = 0;
    elseif v(k+1) <= vlow
        pulseflag = 1;
    end

    % Logging pulseflag value per iteration
    flag(k) = pulseflag;

    % What the displacement
    x(k+1) = x(k)+(v(k+1)/a(k+1));

    k = k+1;
end 
    

timeon = sum(flag(:))*dt; % Number of iterations when pulseflag = 1 times timestep
totaltime = k*dt; % Number of iterations times timestep, the finish time. 

% Plot of velocity versus displacement
subplot(2,1,1)
plot(x,v)
hold on
yline(vhigh,'--','vHigh')
yline(vlow,'.','vLow')
hold off
grid on
title('Velocity Vs Displacement')
xlabel('Displacement')
ylabel('Velocity')
ylim([0, 7])


% Plot of velocity versus time
timemaster = linspace(0,k*dt,length(v));

subplot(2,1,2)
plot(timemaster,v)
hold on
yline(vhigh,'--','vHigh')
yline(vlow,'.','vLow')
hold off
grid on
title('Velocity Vs Time')
xlabel('Time')
ylabel('Velocity')
ylim([0, 7])

Why do I receive the error message Warning: Marker input is ignored?

Answer 1

[Walter Roberson]

'.' is a marker style not a line style. yline ignores markers

https://www.mathworks.com/help/matlab/ref/yline.html#mw_90060888-a6f9-4742-8f31-03f5f74efd2c_sep_mw_a3e9a047-b69c-4d3e-8106-0713e34b50ef

[Andy]

OK. Thanks. What changes to the script do you reccomend?

[Walter Roberson]

yline(vhigh,'--','vHigh')

That line is fine, because '--' is a valid line style.

yline(vlow,'.','vLow')

That line has a problem, because '.' is a marker style rather than a line style. Consider using '-.' line style, or using different colors for the different lines.

[Andy]

Thanks.