RE : passing functions as argument one more time


> -----Message d'origine-----
> De : maxima-bounces at math.utexas.edu 
> [mailto:maxima-bounces at math.utexas.edu] De la part de amli at comcast.net
> Envoy? : vendredi 6 octobre 2006 21:15
> ? : maxima at math.utexas.edu
> Objet : [Maxima] passing functions as argument one more time
> 
> 
> 1.  How can I make sure that the functions defined in global 
> space do not conflict with passing of 
> function arguments? For example I do not want f(x) defined 
> outside the program  conflict with passing the function f.   
> (In a scipt file I may have many functions defined)
> 

The only way that I know for that is to make the argument name "unconflictuable"
May be something like:

F(x_%_1):=...

Note that you can use: declare (char, alphabetic) to adds char to Maxima's alphabet.

> 
> x:5;
> t:3;
> ff(f,x):=block([t,g,h],g:apply('f,[t]),if x<1 then h(x):=x 
> else h(x):=3*x,ev(g,t=x)*h(2*x));
> ff(sin,2);    //works
> 
> 
> f(x):=x^2;
> ff(f,x):=block([t,g,h],g:apply('f,[t]),if x<1 then h(x):=x 
> else h(x):=3*x,ev(g,t=x)*h(2*x)); ff(sin,2);  //does not work
> 
> I tried this 
> (x):=x^2;
> ff(f,x):=block([t,g,h],g:'apply('f,[t]),if x<1 then h(x):=x 
> else h(x):=3*x,ev(g,t=x)*h(2*x)); ff(sin,2);  
> but how do you get the final evaluation.
> 
> 2.  I also do not want the functions defined inside the 
> program such as h have global scope.  How can I restrict them 
> to be local only.   I suppose I could use the kill command.  
> Is that the only solution?
> 

You can embed function definition in block like this:

ff(f_%, x_%) := block(
  [t, g, h],
  g : apply('f_%,[t]),
  if x_% < 1 then (
    block(
      h(x_%) := x_%,
      return( ev(g, t = x_%) * h(2 * x_%) )
    ) 
  ) else (
    block(
      h(x_%) := 3 * x_%,
      return( ev(g, t = x_%) * h(2 * x_%) ) 
    )
  )
);


Laurent.