How to solve for a variable multiple times using a for loop.

I need to solve a nonlinear equation multiple times and plot the results. The equation is based on V, which is a constant, T, k & Kc, which both depend on T, and X. I'm trying to plot X as a function of T but can't seem to figure it out. When I attempt to use a for loop, I receive the error "Error using mupadmex Error in MuPAD command: Operands are invalid. [linalg::matlinsolve]".

x=1
for T = [300;1;400]
  syms X
  V = 3785.411784;
  k = 1/2902.149*exp(15000*4.184/8.314*(1/300-1/T))
  Kc = 3*exp(-25000*4.184/8.314*(1/300-1/T));
  eqn = X/k/((1-X)^2-X^2/Kc)-V == 0;
  Solution = double(vpasolve(eqn, X, [0 1]))
  Solmat(x,1) = T;
  Solmat(x,2) = Solution;
  x=x+1;
end

Answer 1

[Star Strider]

The problem is the semicolons (;) in the ‘T’ assignment at the start of the loop. Replace it with:

for T = [300:1:400]

and your code runs.

Also, you don’t need to define the ‘1’ step, since that is the default step value in colon (:) operator generated vectors.

[Cyrus Azizzadeh]

How can I use "solve" command in "for loop"? My code:

Clc Clear all Syms t phi theta phi1 theta1 d=5; ss(1,1)=0 ss(1,2)=0

For t=5:5:350 A((t/5),1)= expression (t,phi,theta,phi1,theta1)

B((t/5),1)= expression (t,phi,theta,phi1,theta1)

A1((t/5),1)=subs(A((t/5),1),[phi,theta],[ss((t/5),1),ss((t/5),2])

B1((t/5),1)=subs(B((t/5),1),[phi,theta],[ss((t/5),1),ss((t/5),2]) s((t/5),1)= solve('A1((t/5),1)','B1((t/5),1)') s((t/5))=[s.phi1 s.theta1] ss((t/5))=eval(s((t/5))) end ss

[Star Strider]

Post this as a new question. produce something meaningful for ‘expression’.

There are so many errors in that code I am not even going to attempt to correct them.

I will delete your Comment and this one in a few hours.