diff options
author | mrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-03-23 12:41:00 +0000 |
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committer | mrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-03-23 12:41:00 +0000 |
commit | e324d29e2b5f78c3b38b293e19976205d6fcdb7d (patch) | |
tree | 32cb85a9607db1a3c17d8b4da54e090ede05b867 /enum.c | |
parent | 5396d8a1ab52b4da4f5199109472fe7f8ea43085 (diff) |
* enum.c (ary_inject_op): Use Kahan's compensated summation algorithm
for summing up float values.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54237 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'enum.c')
-rw-r--r-- | enum.c | 15 |
1 files changed, 11 insertions, 4 deletions
@@ -634,7 +634,7 @@ ary_inject_op(VALUE ary, VALUE init, VALUE op) ID id; VALUE v, e; long i, n; - double f; + double f, c; if (RARRAY_LEN(ary) == 0) return init == Qundef ? Qnil : init; @@ -686,16 +686,23 @@ ary_inject_op(VALUE ary, VALUE init, VALUE op) rb_method_basic_definition_p(rb_cFloat, idPLUS)) { f = RFLOAT_VALUE(v); sum_float: + c = 0.0; while (1) { + double y, t; e = RARRAY_AREF(ary, i); if (RB_FLOAT_TYPE_P(e)) - f += RFLOAT_VALUE(e); + y = RFLOAT_VALUE(e) - c; else if (FIXNUM_P(e)) - f += FIX2LONG(e); + y = FIX2LONG(e) - c; else if (RB_TYPE_P(e, T_BIGNUM)) - f += rb_big2dbl(e); + y = rb_big2dbl(e) - c; else break; + + t = f + y; + c = (t - f) - y; + f = t; + i++; if (RARRAY_LEN(ary) <= i) return DBL2NUM(f); |