F# performance in scientific computing

Question

I am curious as to how F# performance compares to C++ performance? I asked a similar question with regards to Java, and the impression I got was that Java is not suitable f

Answer 1

Firstly C is significantly faster than C++.. So if you need so much speed you should make the lib etc in c.

With regards to F# most bench marks use Mono which is up to 2 * slower than MS CLR due t partially to its use of the boehm GC ( they have a new GC and LVVM but these are still immature dont support generics etc).

.NEt languages itself are compiled to an IR ( the CIL) which compile to native code as efficiently as C++. There is one problem set that most GC languages suffer in and that is large amounts of mutable writes ( this includes C++ .NET as mentioned above) . And there is a certain scientific problem set that requires this , these when needed should probably use a native library or use the Flyweight pattern to reuse objects from a pool ( which reduces writes) . The reason is there is a write barrier in the .NET CLR where when updating a reference field (including a box) it will set a bit in a table saying this table is modified . If your code consists of lots of such writes it will suffer.

That said a .NET app like C# using lots of static code , structs and ref/out on the structs can produce C like performance but it is very difficult to code like this or maintain the code ( like C) .

Where F# shines however is parralelism over immutable data which goes hand and hand with more read based problems. Its worth noting most benchmarks are much higher in mutable writes than real life applications.

With regard to floating point , you should use an alternative lib ( ie the .Net one) to the oCaml ones due to it being slow. C/C++ allows faster for lower precision which oCaml doesnt by default.

Lastly i woudl argue a high level language like C#, F# and proper profiling will give you betetr pefromance than c and C++ for the same developer time. If you change a bottle neck to a c lib pinvoke call you will also end up with C like performance for critical areas. That said if you have unlimited budget and care more about speed then maintenance than C is the way to go ( not C++) .