Error in mat2str function

Hi, I have the following code that implements the Newton method for nonlinear systems. This code works in matlab 2010 but not in 2013.Tells me that's a input matrix must be numeric

    if true

clear;
clc;
syms x1 x2 x3 x4 x5 x6 x7 x8 x9 x y z w t;
vars=input('Tell vector (line) of the variables=');
F=input('Tell vector (line) of the equations =');
J=jacobian(F,vars);
X=input('Tell vector (line) initial approach =');
erro=input('Tell precision error =');
itmax=input('Enter the maximum number of iterations =');
e=erro+1;
it=0;
while(e>erro && it<itmax)
    X0=X;
    FX=subs(F,vars,X)
    JX=subs(J,vars,X)
    delta=JX\(-FX)'
    X=X+delta'
    e=norm(delta,inf)
    disp(['X(transposed)=',mat2str(X),' Error=',num2str(e),' iteration=',num2str(it)]);
    it=it+1;
end  
end

   How can I fix this?

The input is:
[x1 x2]
[x1^2+(x2-2)^2-9 (x1-1)^2+x2^2-2]
[-0.1 -1]
0.01
20

and the output should be: 
X=[-4.05844155882936e-06 -1.00000202922078] Error=0.0031209 iteration=2

Can anyone help me? I appreciate any help...

Thanks

Answer 1

[Prateekshya]

Hi Leandro,

As per my understanding the error is caused since you are passing symbolic variables to the "mat2str" and the "num2str" functions. These functions are updated and they take only numeric values as input. The following change in your code gives the correct output.

disp(['X(transposed)=',mat2str(double(X)),' Error=',num2str(double(e)),' iteration=',num2str(it)]);

The "double" function ensures that the symbolic variables are converted to corresponding double values leading to error free execution of the code.

I hope this helps!

Thank you.