Thread overview
[Issue 4874] New: std.numeric.dotProduct doesn't work with bigints
Sep 15, 2010
Don
September 15, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4874

           Summary: std.numeric.dotProduct doesn't work with bigints
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc
        Depends on: 4872


--- Comment #0 from bearophile_hugs@eml.cc 2010-09-15 14:17:17 PDT ---
With dmd 2.049beta this code compiles (but first see bug 4872 too):


// program #1
import std.bigint;
T dotProduct2(T)(/*in*/ T[] a1, /*in*/ T[] a2) {
    assert(a1.length == a2.length);
    T total = 0;
    foreach (i; 0 .. a1.length)
        total += a1[i] * a2[i];
    return total;
}
void main() {
    BigInt[] a1 = [BigInt(1), BigInt(3), BigInt(-5)];
    BigInt[] a2 = [BigInt(4), BigInt(-2), BigInt(-1)];
    BigInt r = dotProduct2(a1, a2);
}



But the std.numeric.dotProduct() can't be used with bigints:


// program #2
import std.numeric, std.bigint;
void main() {
    BigInt[] a1 = [BigInt(1), BigInt(3), BigInt(-5)];
    BigInt[] a2 = [BigInt(4), BigInt(-2), BigInt(-1)];
    assert(dotProduct(a1, a2) == BigInt(3));
}


If in program #1 arguments are "in" it doesn't compile.

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September 15, 2010
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Andrei Alexandrescu <andrei@metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei@metalanguage.com
         AssignedTo|nobody@puremagic.com        |andrei@metalanguage.com


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Don <clugdbug@yahoo.com.au> changed:

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                 CC|                            |clugdbug@yahoo.com.au


--- Comment #1 from Don <clugdbug@yahoo.com.au> 2010-09-15 15:11:49 PDT ---
That's the same issue as 4301. BigInt isn't yet const-correct.

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March 11, 2013
http://d.puremagic.com/issues/show_bug.cgi?id=4874



--- Comment #2 from Andrei Alexandrescu <andrei@erdani.com> 2013-03-10 19:20:19 PDT ---
Assigning to Don.

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