[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568 Don changed: What|Removed |Added Status|NEW |RESOLVED Resolution||FIXED --- Comment #7 from Don 2011-02-23 13:34:57 PST --- Fixed: https://github.com/D-Programming-Language/phobos/commit/9ecf947290f1149e1b062a75dafd30326697fe00 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568
--- Comment #6 from Don 2011-02-19 06:13:57 PST ---
And the original test case is:
import std.bigint;
void main() {
BigInt m = (BigInt(1) << (4846+4843) ) - 1;
BigInt a = (BigInt(1) << 4846 ) - 1;
BigInt b = (BigInt(1) << (4846*2 + 4843)) - 1;
BigInt c = (BigInt(1) << (4846*2 + 4843*2)) - 1;
BigInt w = c - b + a;
assert(w % m == 0);
}
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[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568
--- Comment #5 from Don 2011-02-19 00:50:51 PST ---
Reduced test case:
import std.bigint;
void main() {
enum int Y = 2008;
BigInt m = (BigInt(1) << (Y*1 + 1)) - 1;
BigInt b = (BigInt(1) << (Y*2 + 1)) - 1;
BigInt c = (BigInt(1) << (Y*3 + 1)) - 1;
BigInt w = c - b;
w = w % m;
}
This trips an assert when Phobos is compiled in debug mode.
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[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568
--- Comment #4 from Don 2011-02-13 07:24:38 PST ---
(In reply to comment #3)
> (In reply to comment #2)
>
> > Have you tried writefln?
> >
> > import std.stdio;
> > import std.bigint;
> >
> > void main()
> > {
> > BigInt a = 7;
> > a ^^=56;
> > writefln("%x", a);
> > writefln("%s", a);
> > }
>
> I have never tried that. I suggest to add this example to docs of the
> std.bigint module :-)
Yes, although I think it's pretty obvious. The non-obvious thing, is that if
you tried in on 2.050 or earlier, it didn't work... It does now.
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[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568
--- Comment #3 from bearophile_h...@eml.cc 2011-02-13 05:58:03 PST ---
(In reply to comment #2)
> Have you tried writefln?
>
> import std.stdio;
> import std.bigint;
>
> void main()
> {
> BigInt a = 7;
> a ^^=56;
> writefln("%x", a);
> writefln("%s", a);
> }
I have never tried that. I suggest to add this example to docs of the
std.bigint module :-)
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[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568
Don changed:
What|Removed |Added
CC||clugd...@yahoo.com.au
--- Comment #2 from Don 2011-02-13 00:20:33 PST ---
(In reply to comment #1)
> Problem originally found by tsukikage.
>
> A handy printing function for BigInts is really needed in Phobos.
Have you tried writefln?
import std.stdio;
import std.bigint;
void main()
{
BigInt a = 7;
a ^^=56;
writefln("%x", a);
writefln("%s", a);
}
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[Issue 5568] A problem with BigInt modulus
http://d.puremagic.com/issues/show_bug.cgi?id=5568 --- Comment #1 from bearophile_h...@eml.cc 2011-02-12 17:20:01 PST --- Problem originally found by tsukikage. A handy printing function for BigInts is really needed in Phobos. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
