Error in MuPAD command: The dimensions do not match

Hi, I have to do a for cicle in which one variable (k) change and the others variables are costants, but Matlab gives me an error: Error in MuPAD command: The dimensions do not match. I am trying to use the following code (I'm sorry for the length of the equation) to obtain a vectors of results. Then I want to plot KAP as function of k:

    syms F x c k

KAP=(F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k^2*exp(-k*(F + c - x))*(F*exp(-x) - 1) - F*exp(-k*(F + c - x))*exp(-x) + 2*F*k*exp(-k*(F + c - x))*exp(-x) + F*k^2*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1)^2 + 2*F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))/(k*exp(-k*(F + c - x))*(F*exp(-x) - 1) + F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - F*exp(-k*(F + c - x))*exp(-x) + F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))
k=0.1:0.1:0.6
for i=1:length(k)
KAP=(F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k^2*exp(-k*(F + c - x))*(F*exp(-x) - 1) - F*exp(-k*(F + c - x))*exp(-x) + 2*F*k*exp(-k*(F + c - x))*exp(-x) + F*k^2*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1)^2 + 2*F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))/(k*exp(-k*(F + c - x))*(F*exp(-x) - 1) + F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - F*exp(-k*(F + c - x))*exp(-x) + F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))
KAP=subs(KAP,{F,x,c,k(i)},{5,4,4,0.1})
KAP=vpa(KAP)
end

Variables like F, x, c have to be constant. Anyone could help me?

Answer 1

[Walter Roberson]

    syms F x c k

KAPeqn = (F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k^2*exp(-k*(F + c - x))*(F*exp(-x) - 1) - F*exp(-k*(F + c - x))*exp(-x) + 2*F*k*exp(-k*(F + c - x))*exp(-x) + F*k^2*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1)^2 + 2*F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))/(k*exp(-k*(F + c - x))*(F*exp(-x) - 1) + F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - F*exp(-k*(F + c - x))*exp(-x) + F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1));

 kvals = 0.1:0.1:0.6;

 for i = 1 : length(kvals)
   KAP(i) = vpa(subs(KAPeqn,{F,x,c,k},{5,4,4,kvals(i)}));
 end

plot(kvals, KAP);

Answer 2

[PIERLUIGI PEDERZOLI]

Thanks a lot. Now it works well. How can I see all the steps of the scripts in the command window with the numeric value that KAPeqn assumes when k change?

[Walter Roberson]

syms F x c k

KAPeqn = (F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - k^2*exp(-k*(F + c - x))*(F*exp(-x) - 1) - F*exp(-k*(F + c - x))*exp(-x) + 2*F*k*exp(-k*(F + c - x))*exp(-x) + F*k^2*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1)^2 + 2*F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1))/(k*exp(-k*(F + c - x))*(F*exp(-x) - 1) + F*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F)) - F*exp(-k*(F + c - x))*exp(-x) + F*k*exp(-x)*exp(-k*(F + c - x - (exp(F) - exp(x))/F))*(exp(x)/F - 1));
   kvals = 0.1:0.1:0.6;
   for i = 1 : length(kvals)
     KAPi = vpa(subs(KAPeqn,{F,x,c,k},{5,4,4,kvals(i)}))
     KAP(i) = KAPi;
   end

plot(kvals, KAP);

Answer 3

[PIERLUIGI PEDERZOLI]

Again thank you!