"Samuel Marchal" <samuel.marchal@gazdefrance.com> wrote in message
news:eee70a0.1@webx.raydaftYaTP...
> Hello,
>
> I have created a formal function of one parameter with the command
> "inline" and then I apply the command fminbnd on this function.
>
> Now I would like to create a formal function of several parameters to
> use the command fminbnd on this function.
>
> I can't apply fminbnd command on a simple example when I define a
> simple function of a vector. (example : f(x) = x(1)+x(2))
>
> I can't apply fminbnd command on a complex expression with several
> parameters.
>
> If I define an inline function, Matlab gives me the following error
> message after applying the fminbnd command on the function:
>
> ??? Error using ==> inline/horzcat Inline functions can't be
> concatenated.
>
> If I don't define an inline function, Matlab gives me the following
> error message :
>
> ??? Error using ==> horzcat All matrices on a row in the bracketed
> expression must have the same number of rows.
>
> Do you know if it exists a command to create formally and to
> concatenate functions of several parameters or vectors? Then I could
> apply fminbnd command on this formal function.
With inline objects, it's a bit tricky.
f1 = inline('sin(x)', 'x');
f2 = inline('feval(fofx, y.^2)', 'y', 'fofx');
z = fminbnd(f2, 1, 1, optimset('Display', 'iter'), f1)
Note that I passed the inline function to be evaluated as an input to the
second inline function. [Like I said, it's a bit tricky.]
If you're using MATLAB 7.0 (R14), I recommend using anonymous functions
instead:
f1 = @(x) sin(x);
f2 = @(y) f1(y.^2);
z = fminbnd(f2, 1, 1, optimset('Display', 'iter'))
This looks (at least in my opinion) a lot cleaner, and doesn't require you
to pass inline functions as inputs to other inline functions. Personally
I'd put the definition of f2 inside the call to FMINBND if possible:
f1 = @(x) sin(x);
z = fminbnd(@(y) f1(y.^2), 1, 1, optimset('Display', 'iter'))
This way there are fewer things that could be accidentally modified between
when you define your functions and when you use them.

Steve Lord
slord@mathworks.com
