Re: passing functions handles to functions

[David Bateman]

Christophe Prud'homme wrote:

> Hi again,
>
> In octave, you can define function using 'function' and 'inline'
> however functions like 'fzero' accepts only functions defined by
> 'function' (and not inline)
>
> for example
> ---------------------------
> function y = fun(x)
>   y = x.^2 - 1 + exp(x);
> end
>
> fzero("fun", 1)
> ---------------------------
> Ok
>
> but
>
> --------------------------
>  f=inline('x.^2 - 1 + exp(x)')
> f =
>
> f(x) = x.^2 - 1 + exp(x)
>
> octave:2> argnames(f)
> ans =
>
> {
>   [1,1] = x
> }
>
> octave:3> fzero('f',1)
> error: feval: the symbol `f' is not valid as a function
> error: evaluating assignment expression near line 358, column 5
> error: evaluating if command near line 208, column 2
> error: called from `fzero' in file
> `/usr/share/octave/site/m/octave-forge/optim/fzero.m'
> -------------------------
>
>
> in matlab inline, and strings can be used.
>
> is there a general rule in octave regarding passing function handles  ?
> like you can pass only functions handles of functions defined using
> 'function' ?
> or does it depend on the function using the function handle like fzero ?
> or am I missing something ?
>
> Best regards
> C.
>

With both octave cvs and 2.1.71 I can do

f = @cos;
feval(f,0)
ans = 1

so feval accepts function handles. fsolve, daspk and a few other things
don't for rather complex reason that basically mean all of the
underlying fortran code for these function would need to be replaced to
make the patched needed to fully implement this not be an enormous
kludge.. See the threads

http://www.octave.org/mailing-lists/octave-maintainers/2005/869
http://www.octave.org/mailing-lists/octave-maintainers/2005/72
http://www.octave.org/mailing-lists/octave-maintainers/2004/627

D.

-- 
David Bateman                                address@hidden
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