Q: compiling causes problems in evaluating functions?

You should probably set T_C to 264.0d0 rather than 264.

Also I suggest you set twopi:2*?pi
And use that, to improve speed.

Is it a compiler error?  
Maybe if you think that the compiled code should check for incorrect types
of numeric data.
RJF

 

> -----Original Message-----
> From: maxima-bounces at math.utexas.edu 
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Robert Gloeckner
> Sent: Sunday, April 22, 2007 3:54 PM
> To: maxima at math.utexas.edu
> Subject: Q: compiling causes problems in evaluating 
> functions?
> 
> Hello,
> 
> I really hope this is my fault...
> [maxima 5.9.10 on Linux]
> 
> my code:
> --------------------------------
> A_N:1e+21;
> B_N:30;
> T_C:264;
> eq4_7_(T, _p) :=  (A_N / sqrt(2.0 * %pi * B_N * B_N)) *
>                    exp(-0.5 * ((T - T_C) / B_N)^2 );
> ---------------------------------
> 
> 
> (%i95) eq4_7_(T, _p)      :=  (A_N / sqrt( 2.0 * %pi * B_N * B_N)) *
> exp(-0.5 * ((T - T_C) / B_N)^2 );
> 
> 				  A_N			    T - T_C 2
> (%o95)  eq4_7_(T, _p) := --------------------- exp((- 0.5) (-------) )
> 			 sqrt(2.0 %pi B_N B_N)		      B_N
> (%i96) eq4_7_(xx,yy);
> 
> 								   2
> 				  - 5.555555555555556E-4 (xx - 264)
> 	  2.357022603955158E+19 %e
> (%o96) 	  
----------------------------------------------------------
> 				  sqrt(%pi)
> (%i97) compile(eq4_7_);
> 
> Compiling gazonk0.lsp.
> End of Pass 1.
> End of Pass 2.
> OPTIMIZE levels: Safety=2, Space=3, Speed=2
> Finished compiling gazonk0.lsp.
> (%o97) 				   [eq4_7_]
> (%i98) eq4_7_(xx,yy);
> 
> (%o98)
> 								
> 	      2
> 			  - 5.555555555555556E-4 (xx - 
> 2.121995921398603E-314)
>   2.357022603955158E+19 %e
> 
> --------------------------------------------------------------
> ---------------
> 				    sqrt(%pi)
> (%i99)
> 
> 
> How can that be? I need to use compile, because otherwise evaluation
> functions (numerical integration) take much too long. What is the
> problem in this case?
> Can somebody verify this behaviour?
> If it is a bug - is this fixed in more recent versions of maxima?
> 
> Thanks
> Robert
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