Solving Equation (Updated!)

Hello,

I already posted the similar question and someone answered it. However, I've deleted what I posted because I found serious problems in my code. I apologize to the person who answered to my question. Now, the following code I've constructed only gives an error. For your information, I used "arrays" instead of single variables for the purpose of plotting later on. I've included the error message I had. Would you help me to address the problem?

format long e
theta=0.01; 
n=1:1:20;
m=1:1:10;
x=zeros(length(n),length(m));
gamma_REA=zeros(1,length(m));
equation1=zeros(length(n),length(m));
equation2=zeros(length(n),length(m));
equation=zeros(length(n),length(m));

gamma_REA(1)=10.0;

for i=1:1:length(n)
    for j=1:1:length(m)       
    equation1(i,j)=1+[x(i,j)/(1+x(i,j))]^n(i).*(gamma_REA(j)-1);
    equation2(i,j)=1+[x(i,j)/(theta+x(i,j))]^n(i).*(gamma_REA(j)-1);
    equation(i,j)=theta*equation1(i,j)./equation2(i,j)-[(theta+x(i,j))/(1+x(i,j))].^(n(i)+1)==0;
    sol=vpasolve(equation,x(i,j));
    fprintf('%d %.10e %.10e\n',i,gamma_REA(j), min(sol(sol>0.0)));   
    gamma_REA(j+1)=gamma_REA(j)*10.0;
    end   
    gamma_REA(1)=10.0;
end

See the error message:

Undefined function 'vpasolve' for input arguments of type 'double'.

Error in error_fraction4_test (line 67) sol=vpasolve(equation,x(i,j));

Answer 1

[Naman Chaturvedi]

Hello,

You didn't use the 'vpasolve' function correctly. The first argument of the function 'vpasolve' should be the equation and the second the variable for which you want the equation to be solved. I maybe able to help you better if you could provide me the intent of this code. Also, consider reading this document on vpasolve.

[onsagerian]

Hello,

Thank you for your comment.

The code was designed to solve the equation, giving each numerical value depending on the variables i and j. This part corresponds to "sol=vpasolve(equation,x(i,j))".

In particular, I am interested in fining out solutions satisfying the condition, the minimum values among positive solutions (min(sol(sol>0.0))).

I would appreciate if you would help me.