Re: Passing functions as parameters

[A Scottedward Hodel]

No, you need to define a value of x in order to evaluate the string.

You could alternatively do something like (try-catch syntax probably
messed up here):

function y = arbfunc(x,f)
## y = arbfunc(x,f)
## evaluate an arbitrary function f at x
##  x: value
##  f: function of x (string)
  try
    y = eval(f);
  catch
    error("Trouble evaluating %s at %g",f,x);
  endtrycatch
endfunction

> A Scottedward Hodel wrote:
> >  Short answer: pass it as a string,
> >          str = "sin(x)+log(x^2+x) "
> >  then use
> >          fx = eval(str);
> >  to evaluate the function.
> >
> >  Not pretty, but it works.
> Are you sure? I got the following:
>
> octave:5> str = "sin(x)+log(x^2+x)"
> str = sin(x)+log(x^2+x)
> octave:6> fx = eval(str);
> error: `x' undefined near line 5 column 5
> error: evaluating expression near line 5, column 5
> error: evaluating argument list element number 1
> error: evaluating index expression near line 5, column 1
> error: evaluating binary operator `+' near line 5, column 7
> error: evaluating assignment expression near line 5, column 7
> error: evaluating index expression near line 6, column 6
> error: evaluating assignment expression near line 6, column 4 
>
> I have Octave version 2.0.16. Maybe this feature is working only in a
> development version?
>
>         Kind regards
>                 Dejan

--
A S Hodel Assoc. Prof. Dept Elect and Computer Eng, Auburn Univ,AL 36849-5201
On leave at NASA Marshall Space Flight Center (256) 544-1426
Address until 31 July 2000:Mail Code TD-55, MSFC, Alabama, 35812
http://www.eng.auburn.edu/~scotte



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