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pairwise sum returns double for ranges with float elements

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Andrei Alexandrescu 2014-01-25 14:42:37 -08:00
parent 7783916096
commit 637bd45413
1 changed files with 7 additions and 3 deletions
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10
std/algorithm.d
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@ -1082,12 +1082,12 @@ unittest
} }
// Pairwise summation http://en.wikipedia.org/wiki/Pairwise_summation // Pairwise summation http://en.wikipedia.org/wiki/Pairwise_summation
ElementType!R sum(R)(R r) auto sum(R)(R r)
if (hasSlicing!R && hasLength!R && isFloatingPoint!(ElementType!R)) if (hasSlicing!R && hasLength!R && isFloatingPoint!(ElementType!R))
{ {
switch (r.length) switch (r.length)
{ {
case 0: return 0; case 0: return 0.0;
case 1: return r.front; case 1: return r.front;
case 2: return r.front + r[1]; case 2: return r.front + r[1];
default: return sum(r[0 .. $ / 2]) + sum(r[$ / 2 .. $]); default: return sum(r[0 .. $ / 2]) + sum(r[$ / 2 .. $]);
@ -1097,7 +1097,11 @@ if (hasSlicing!R && hasLength!R && isFloatingPoint!(ElementType!R))
unittest unittest
{ {
static assert(is(typeof(sum([1., 2., 3., 4.])) == double)); static assert(is(typeof(sum([1., 2., 3., 4.])) == double));
static assert(is(typeof(sum([1F, 2F, 3F, 4F])) == float)); static assert(is(typeof(sum([1F, 2F, 3F, 4F])) == double));
const(float[]) a = [1F, 2F, 3F, 4F];
static assert(is(typeof(sum(a)) == double));
const(float)[] b = [1F, 2F, 3F, 4F];
static assert(is(typeof(sum(a)) == double));
double[] empty; double[] empty;
assert(sum(empty) == 0); assert(sum(empty) == 0);