Register to reply 
Compiled Functions in Mathematica 
Share this thread: 
#1
Mar912, 02:36 PM

P: 25

Hello,
I was looking at ways I could optimize a simulation I wrote in Mathematica and came across the command compile. From what I understand, it defines a function that expects a numerical value for the variable. But I don't understand how this would be any different from just ordinarily defining a function using " := " 


#2
Mar912, 07:57 PM

P: 1,037

When not inside a Compile[] something like + has to check
Is this a symbol, if so then do this Is this a decimal approximation, if so then do this Is this a matrix, if so then do this ... All the checking adds a considerable overhead. When inside a Compile[] the rules are very different. It invokes a much more limited set of sanity checks, if those fail it defaults back to the uncompiled code, otherwise it invokes something similar to a Java byte code machine which simulates a virtual CPU to do mostly numerical calculations. For the right kinds of problems with a really well implemented algorithm inside Compile[] you can see 530x increase in speed. But Compile[] is at or near the top of the list for worst documented functions available. There are tiny little examples here and there in books and you can try to reverse engineer what the documentation should be to use it effectively. I am mostly serious with my offer to buy a cake for the first person to write a really really well done tutorial on how to write a Compile[] so that it will always do what I want fast and will work the first time. Thus far I have had zero nibbles on that. You can also consider MathLink to an outside executable. If you can put almost everything you need to do into that executable and have minimal communication then that can provide you even greater speed. 


Register to reply 
Related Discussions  
Mathematica: Interpolation Functions  Math & Science Software  3  
Definiing two functions (mathematica)  Math & Science Software  3  
Using interpolating functions in Mathematica  Math & Science Software  1  
Mathematica functions  Math & Science Software  1  
A list of functions in Mathematica?  Math & Science Software  3 