MATLAB: Plotting the graph, help me~~

error

The above graph is the purpose that i want.
The below is the code and it has errors. Whats the problem? Please suggest the code. Thanks
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W=40;
Vth=0.45;
Leff=0.15;
k=4.255*(10^-4)*(W/Leff);
lambda=25*10^-5;
Vgs=linspace(0,2);
vds=[0.2 1 2];
m=length(Vgs);
for k1 = 1:numel(vgs)
for i=1:m
if vgs(k1) < Vth
current(k1,i)=0;
elseif Vds(i) >= (vgs(k1) – Vth)
current(k1,i)=0.5* k * ((vgs(k1) – Vth).^2);
elseif Vds(i) < (vgs(k1) – Vth)
current(k1,i)= k*((vgs(k1)-Vth)*Vds(i) – 0.5*(Vds(i).^2));
end
end
end
figure
plot(Vgs,current, 'LineWidth',1.5)
————————————————————————————————————————
error: 'current' undefined near line 1, column 1
error: 'vgs' undefined near line 1, column 1

Best Answer

You had a few mismatches between vgs and Vgs. Matlab is case sensitive. Try
W=40;
Vth=0.45;
Leff=0.15;
k=4.255*(10^-4)*(W/Leff);
lambda=25*10^-5;
Vgs=linspace(0,2,5);
Vds=[0.2 1 2];
m=length(Vds);
for k1 = 1:numel(Vgs)
for i=1:m
    if Vgs(k1) < Vth
        current(k1,i)=0;
    elseif Vds(i) >= (Vgs(k1) - Vth)
        current(k1,i)=0.5* k * ((Vgs(k1) - Vth).^2);
    elseif Vds(i) < (Vgs(k1) - Vth)
        current(k1,i)= k*((Vgs(k1)-Vth)*Vds(i) - 0.5*(Vds(i).^2));
    end
end
end
figure
plot(Vgs,current, 'LineWidth',1.5)
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