Also...pseudo-random number generation is not a specific computation; there
are many ways to do it--some faster some slower, some better some worse. If
you want to time a general poisson disc simulation you would be better with
a grid than calls to rand() because now you are testing the speed of the
chosen random number generator.
For comparison, your fmt.Println(calPi(100000000)) with the standard
(locking) prng on my notebook:
3.14151812
real 0m5.123s
versus a one-thread high-quality prng:
3.14154348
real 0m1.395s
The speedup shows that you are just testing random number generation speed.
The same computation with a grid of pointCount points...
root := math.Sqrt(float64(pointCount))
d := 2 / root
for x := -1.0; x < 1.0; x += d {
for y := -1.0; y < 1.0; y += d {
if x*x+y*y < 1 {
inCircleCount++
}
}
}
...gives:
3.14158668
real 0m0.170s
So, 5.123 or 1.395 or 0.170 seconds based on how the sample points are
calculated. Performance testing is hard.
Michael
On Thu, Jan 24, 2019 at 8:48 PM Ian Lance Taylor <i...@golang.org> wrote:
> On Thu, Jan 24, 2019 at 7:01 PM Karthik Krishnaswamy
> <karthik.krishnaswam...@gmail.com> wrote:
> >
> > I am just curious to understand what is the best possible way to
> increase the execution speed of this particular program ? I am still
> learning go though :)
>
> To speed up that particular program, don't use recursive Fibonacci.
> The recursive function that you wrote has complexity O(2 ** N). Write
> a simple loop, complexity O(N).
>
> Ian
>
>
> > On Fri, Jan 25, 2019 at 8:26 AM Ian Lance Taylor <i...@golang.org>
> wrote:
> >>
> >> On Thu, Jan 24, 2019 at 6:21 PM Topget <topget1...@gmail.com> wrote:
> >> >
> >> > I have tested several simple functions with Golang and Java. To my
> surprise, Java sometimes is faster than Golang（especially in recursive
> function and some function in standard library such as math/rand.Rand）. I
> wonder why. Here is some code I used for test and the result.
> >>
> >> Because goroutines start with a small stack that grows as needed,
> >> deeply recursive functions will tend to have somewhat worse behavior
> >> the first time they are called.
> >>
> >> Ian
> >>
> >> --
> >> You received this message because you are subscribed to the Google
> Groups "golang-nuts" group.
> >> To unsubscribe from this group and stop receiving emails from it, send
> an email to golang-nuts+unsubscr...@googlegroups.com.
> >> For more options, visit https://groups.google.com/d/optout.
>
> --
> You received this message because you are subscribed to the Google Groups
> "golang-nuts" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to golang-nuts+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>
--
*Michael T. jonesmichael.jo...@gmail.com <michael.jo...@gmail.com>*
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
