Another lame question : defining function by a result.



Thank you. The fact, that at A := B the B is not
evaluated explains all...


--- "Viktor T. Toth" <vttoth@vttoth.com> wrote:

> Try define(f(x),%o2); it'll work.
> 
> The reason is simple: when you define a function
> with :=, the RHS is NOT
> evaluated. In other words, your function definition
> will contain the SYMBOL
> %o2, not its value. When you use define(), the
> second argument IS evaluted:
> 
> (%i5) define(f(x),%o2);
>                                              2 x + 1
>                            2           
> ATAN(-------)
>                       LOG(x  + x + 1)        SQRT(3)
>    LOG(x - 1)
> (%o5)       f(x) := - --------------- -
> ------------- + ----------
>                              6             SQRT(3)  
>        3
> 
> Compare this with your line %o3.
> 
> 
> Viktor
> 
> 
> -----Original Message-----
> From: maxima-admin at math
> [mailto:maxima-admin@math.utexas.edu] On
> Behalf Of Jordan Tuzsuzov
> Sent: Wednesday, December 22, 2004 8:08 AM
> To: maxima@math.utexas.edu
> Subject: Another lame question : defining
> function by a result.
> 
> Hello,
> 
> It is just about the expectance of work. I want to
> define a function f(x) by a result of previous
> calculation, related to x. Example :
> (%i1) 1 / ( x^3 - 1 );
> 				      1
> (%o1) 				    ------
> 				     3
> 				    x  - 1
> (%i2) integrate(%,x);
> 					 2 x + 1
> 		       2	    ATAN(-------)
> 		  LOG(x  + x + 1)	 SQRT(3)    LOG(x - 1)
> (%o2) 	        - --------------- - ------------- +
> ----------
> 			 6	       SQRT(3)	        3
> (%i3) f(x) := %o2;
> (%o3) 				  f(x) := %o2
> (%i4) f(10);
> 					 2 x + 1
> 		       2	    ATAN(-------)
> 		  LOG(x  + x + 1)	 SQRT(3)    LOG(x - 1)
> (%o4) 	        - --------------- - ------------- +
> ----------
> 			 6	       SQRT(3)	        3
> 
> The x is not substituted by 10 in call %i4. Why ?
> 
> Thanx.
> Jordan
> 
> 
> 		
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