[OctDev] Re: inline functions (Corrected source)

[Etienne G. <et...@is...>]

  Hello,

On Sat, Aug 10, 2002 at 04:04:24PM -0400, Paul Kienzle wrote:
# Sure.  Add it to octave forge.  I simplified the while loop a bit, and let

  Good, but "if ! exist (fname), break; endif" is better.

# you use a default parameter of "x".  I wouldn't go much beyond this in
# terms of compatibility --- too many assumptions required about what makes a
# variable and what order the variables should go in. Maybe inline(expr,n) as
# shorthand for inline(expr,"x","P1","P2",...,"Pn") is useful.

  Or "x1", "x2", ... ? Does Matlab do such a thing? I would keep it as
it is. I'll check in your version w/ "x" as default but won't do more
refinements.

  Cheers,

  Etienne

# Paul Kienzle
# pki...@us...
# 
# On Sat, Aug 10, 2002 at 06:37:46PM +0100, Etienne Grossmann wrote:
# > 
# >   Sorry, there was a part missing from the first attached func. Try
# > the following.
# > 
# >   Etienne
# > 
# > On Sat, Aug 10, 2002 at 01:32:42PM +0000, Steffan Berridge wrote:
# > # 
# > # Hi,
# > # 
# > # I have just started using Octave, having used Matlab for a
# > # while.  In Matlab I have often used inline functions, they
# > # are very convenient for example when passing a function as
# > # an argument.
# > # 
# > # For example, the following is a function returning the
# > # square of the argument:
# > # 
# > # fun = inline('x^2','x');
# > # 
# > # One can then pass this function as an argument to another
# > # function:
# > # 
# > # x = foo(fun,...);
# > # 
# > # So my question is, is there an equivalent construction in
# > # Octave?  If not, what is the best way to pass functions as
# > # arguments?
# > # 
# > # Thanks,
# > # Steffan
# > -- 
# > Etienne Grossmann ------ http://www.isr.ist.utl.pt/~etienne
# 
# ## [fname,fcode] = inline (str,arg1,...) - Define a function from a string
# ##
# ## INPUT : -----------
# ## str   : string    : String defining the result of the function
# ## argN  : string(s) : Names of the arguments of the function
# ##
# ## OUTPUT : ----------
# ## fname : string    : Name of the new function, which can e.g. be called w/
# ##                     feval() 
# ## fcode : string    : The code of the function
# ##
# ## EXAMPLE : ---------
# ##
# ## fn = inline ("x.^2 + 1","x");
# ## feval (fn, 6)        
# ##   ans = 36
# ##
# function [fname,fcode] = inline (str,varargin)
# 
# ## Choose a name (naive way : won't work zillions of times)
# while 1
#   fname = sprintf ("inline_func_%06i",floor (rand()*1e6));
#   if exist (fname), break; end
# end
# 
# ## construct arg list
# if nargin == 1
#   argstr = "x";
# else
#   argstr = sprintf ("%s,",all_va_args);
#   argstr = argstr(1:length(argstr)-1);
# end
# 
# fcode = sprintf (["function r = %s (%s)\n",\
# 		  "  r = ",str,";\n",\
# 		  "endfunction;"],\
# 		 fname, argstr);
# eval (fcode);
# endfunction		  
# 
# 
# 

-- 
Etienne Grossmann ------ http://www.isr.ist.utl.pt/~etienne