What is the meaning of the error " Inner matrix dimensions must agree".

here am attaching the program

if true
 K=1.38*10^-23;
T=300;
q=1.6*10^-19;
Vt=K*T/q
Nde=2.7*10^19;
Vgs=2;
x=4.6;
Nsdx=Nsdp*exp((-x^2)/(2*lateralstraggle^2))
Nsdp=1*10^20;
eg=1.11;
Eg=1.17;
ni=8.3e9;
lateralstraggle=2;
Lg=70*10^-9;
epsilonox=4;
tsi=2*10^-9;
tox=1.2*10^-9;
epsilon=4;
epsilonsi=2;
Vds=0.1:10;
lambda=((epsilon*tsi*tox)/(2*epsilonox))^1/2
PI=(Vgs-Vfb)-lambda^2*q*(Na-Nsdx)/epsilonsi;
nieff=(ni^2*exp(eg/K*T))^1/2
Vbi=Vt*log(Nde*Na/nieff^2)
fi=Vt*log(Na/ni)
Vfb=1;
seff=log(Nde/Nsdp)*(-2*(lateralstraggle)^2)
leff=Lg-2*seff;
Deff=seff+leff
c2=((Vbi-PI)*(1-(exp(-Deff/lambda))/(exp(-seff/lambda))+Vds))/(exp(Deff/lambda))-(exp(seff/lambda))/(exp(-seff/lambda))*(exp(-Deff/lambda))
%c2=((Vbi-PI)*(1-(exp(-Deff/lambda))/(exp(-seff/lambda))+Vds)/exp(Deff/lambda)-(exp(seff/lambda)/(exp(-seff/lambda)))*exp(Deff/lambda))
c1=(Vbi-c2*exp(seff/lambda)-PI/(exp(-seff/lambda)))
sif=c1*exp(-x/lambda)+c2*exp(x/lambda)+PI;
Na=(ni^2/Na)*exp(sif/Vt);
Vth=Vfb+2*fi-c1*exp(-xmin/lambda)-c2*exp(xmin/lambda)+(lambda^2*q*(Na-Nsdxmin)/epsilonsi);
plot(lateralstraggle,Vth)
ylabel('Vth, V')
xlabel('lateralstraggle,nm')
end

[Wayne King]

If you want somebody to help you, you need to define all the variables which you are using.

For example, you cannot possibly really be defining Ndsp in the line after you use it.

 Nsdx=Nsdp*exp((-x^2)/(2*lateralstraggle^2))
 Nsdp=1*10^20;

Also, how are we supposed to know what Vfb is?

Answer 1

[Wayne King]

That error comes from multiplying matrices which are not conformable,

randn(2,3)*randn(2,3)