40-50ms for each array access
It should be written that each array element takes 1/BarCount part of
total time.
TOTAL time (for half million bars) is 50 ms. So each array element
access time using the loop is about 0.1 MICROsecond (0.0000001 sec).
Generally speaking AFL loops are quite fast.
The following code displays COMMENTARY that shows actual times spent per
bar in both looping and native CPU code.
|GetPerformanceCounter(1);
mycum = 0;
*for* (bar=1; bar<*BarCount*; bar++)
{
mycum[bar] = bar;
}
t1 = GetPerformanceCounter(1);
"Looping code time per bar [ms]" + t1/*BarCount*;
mycum = Cum( 1 );
t2 = GetPerformanceCounter(1);
"Array code time per bar [ms]" + t2/*BarCount*;
"Speed factor between CPU native code (Cum) and loop): " + t1/t2;
Best regards,
Tomasz Janeczko
amibroker.com
|
On 2010-03-08 16:50, jooleanlogic wrote:
For loops and array access, yes there is a significant speed difference in C.
Just think of it this way Sid,
your afl loop in a dll will take about as long as any other inbuilt afl
function does.
If an MA call on your machine takes a few milliseconds, then that's roughly as
long as your afl loop in a dll will take, depending of course on what you're
doing in that loop.
To give you an idea, on my computer, the following simple afl code takes about
200ms on half a million bars. The equivalent Cum(1) call takes about 5ms.
mycum = 0;
for (bar=1; bar<BarCount; bar++){
mycum[bar] = mycum[bar-1] + 1;
}
Going by the Amibroker profiler, it's roughly 100ms for the loop itself and
40-50ms for each array access. In C, the loop itself is virtually a non event
of a few milliseconds, freeing up a couple of hundred ms for your actual code
inside the loop.
This is why you should always try and use the built in functions and array
arithmetic operators where possible.
Jules.
--- In [email protected], "Rob"<sidharth...@...> wrote:
Hi,
Sorry if this is a silly question... but having come a long way with AFL and
feeling like I can do pretty much everything I need to within AFL, I am now
wondering about the use of JScipt/VBScript and DLL's...
In what circumstances would one use JScipt/VBScript or write a custom DLL...?
What are the advantages to their use...?
If someone would be kind enough to just give me a brief outline I'd appreciate
it...
TIA
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