http://d.puremagic.com/issues/show_bug.cgi?id=5240
Summary: Faster std.random.uniform() for [0.0, 1.0) range
Product: D
Version: D2
Platform: All
OS/Version: All
Status: NEW
Severity: enhancement
Priority: P2
Component: Phobos
AssignedTo: nob...@puremagic.com
ReportedBy: bearophile_h...@eml.cc
--- Comment #0 from bearophile_h...@eml.cc 2010-11-19 07:16:51 PST ---
std.random.uniform() is a powerful and flexible function, but some tests show
that it's slow. It also calls nextafter() that is not fast.
A very common use case is the generation of random doubles in the [0.0, 0.1[
range (open on the right). So I suggest to speed up this special case. This
special case is present in the Python standard module "random" too, it is just
named random().
A way to support it is just to add a uniform() that takes no arguments (and
hopefully it doesn't need to call nextafter() inside):
import std.random: uniform;
void main() {
double d = uniform(); // equivalent to uniform(0.0, 1.0) but faster
}
This function that takes no arguments may also have a name like "uniform01()"
or "random()".
Another special case that may be worth supporting is the generation of a random
size_t. This is useful because it avoids using floating point values at all,
and probably minimizes other operations too to generate it, so it may be faster
still than the uniform() with no arguments.
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