fminsearch error regarding matrix dimensions

Hi

I am using fminsearch to minimize the following function:

a_d = 13.2414;
a_nd = 15.5107;
b_d = -1.4207;
b_nd = -1.9339;
Ft = 35;

funct = @(x)a_d*((2*Ft)/(x+1))+b_d+(a_nd*x*((2*Ft)/(x+1)))+b_nd;

[x,fval] = fminsearch(funct, [0, 10]);

But do get the following error:

Error using  / 
Matrix dimensions must agree.

Error in @(x)a_d*((2*Ft)/(x+1))+b_d+(a_nd*x*((2*Ft)/(x+1)))+b_nd

Error in fminsearch (line 191)
fv(:,1) = funfcn(x,varargin{:});

Error in Script (line 22)
[x,fval] = fminsearch(funct, [0, 10]);

What is the problem? Thanks!

Answer 1

[Mischa Kim]

MiauMiau, the function funct has only one dependent variable, x, correct? If so this needs to be reflected in the function call for fminsearch

 [x,fval] = fminsearch(funct, 0);

With your function call

 [x,fval] = fminsearch(funct, [0, 10]);

you assign starting values for a 2-vector, e.g. x1 and x2.

[MiauMiau]

Thanks, that sort of worked, I get:

>> Script

Exiting: Maximum number of function evaluations has been exceeded
         - increase MaxFunEvals option.
         Current function value: -65036482218856192.000000

I want to restrict the x value where fmin is looking for the minima to [0,10] - how could I do that? I guess this would also solve the latest "error". thx!

[Mischa Kim]

Use instead

 [x,fval] = fminbnd(funct,0,10)

[MiauMiau]

prft, thx