Undefined function or variable ' t ',how can I difine ' t ' correctly?

 Hi!
I have defined a function which is:
function [ xs Fxs ] = RevNewton( F, grad, Hess, x, x0 )
where 'F' is the function of 'x'(can be a scalar or a vector),'x0' is the initial value of 'x','grad' and 'Hess' are the gradient vector and Hesse matrix respectively.
In this funtion,I used a varieble 't', which I haven't defined first, to transform the function    F(x) to a function F(t) by using:
subs(F,{x},{x0+t.*p}),
where 'p' is a numerical vector.when using this function,I got an error:

 ??? Undefined function or variable 't'.
 Error in ==> RevNewton at 10
      fhandle=eval(['@(t)',vectorize(subs(F,{x},{x0+t.*p}))]);

Answer 1

[Star Strider]

If I understand ‘9 th row’ correctly, why not just state it as:

fhandle = @(t) vectorize(subs(F,{x},{x0+t.*p}));

Also consider using matlabFunction.

[David W.]

thank you very much,with you suggestion ,I realised that 'eval' is not needed!

[Star Strider]

My pleasure!

Glad we got that sorted!

Answer 2

[MA]

put syms t before giving function F to the program

[David W.]

 I have tied this,but also get an error:

 ??? Error using ==> assignin
 Attempt to add "t" to a static workspace.
 See MATLAB Programming, Restrictions on Assigning to Variables for details.

 Error in ==> syms at 77
      assignin('caller',x,sym(x));

 Error in ==> RevNewton at 6
  syms t;

[MA]

you should get answer with syms x t

[David W.]

If you don't mind,I can give you the full code and you can run it ,it's very simple,only that one error.

[David W.]

 Is that OK ?
 Very appreciated!

[David W.]

 function [ xs Fxs ] = RevNewton( F, grad, Hess, x, x0 )
Hess
  f0 = subs(F,{x},{x0});
  g0 = subs(grad,{x},{x0});
  HS=0;
  while HS==0
  G = subs(Hess,{x},{x0});
  if det(G)==0
      p=-g0;
      fhandle=eval(['@(t)',vectorize(subs(F,{x},{x0+t.*p}))]);
      [a b]=searchint(fhandle,0,1);
      [tg f]=goldenSM(fhandle,0.1,a,b);
      xx=x0+tg.*p;
      g=subs(grad,{x},{xx});
  else
      x1=x0-G\g0;
      f1=subs(F,{x},{x1});
      [xx f g]=revise(F,f0,f1,g0,x0);
  end
   HS = HS(x0,xx,f0,f,g);
   x0 = xx;
   f0 = f;
   g0 = g;
  end  
  xs = xx;
  Fxs = f;
      function [xx f g]=revise(F,f0,f1,g0,x0)
        if f1<f0
          g=subs(grad,{x},{x1});
          f=f1;
          xx=x1;
        else
            if abs(g0.*p)/(norm(g0,2)*norm(p,2))<=0.1
                p=-g0;
            else
                if (g0.*p)/(norm(g0,2)*norm(p,2))<=0.1
                    p=-G\g0;
                else
                    p=G\g0;
                end
            end
         fhandle=eval(['@(t)',vectorize(subs(F,{x},{x0+t.*p}))]);
         [a b]=searchint(fhandle,0,1);
         [tg f]=goldenSM(fhandle,0.1,a,b);
         xx=x0+tg.*p;
         g=subs(grad,{x},{xx});
        end
    end
end

[David W.]

the error is in the 9th. row