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author | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-04-13 13:51:53 +0000 |
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committer | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-04-13 13:51:53 +0000 |
commit | b359d20352163558d4e7550714844f24b568297e (patch) | |
tree | b5932236ea53fb4dc0e1ec1c283566157170c263 /array.c | |
parent | c25853518665c71a79704ca50d40bf2fc4bc6aaa (diff) | |
download | ruby-b359d20352163558d4e7550714844f24b568297e.tar.gz |
* array.c (rb_ary_sum): Array#sum is implemented.
Kahan's compensated summation algorithm for precise sum of float
numbers is moved from ary_inject_op in enum.c.
* enum.c (ary_inject_op): Don't specialize for float numbers.
[ruby-core:74569] [Feature#12217] proposed by mrkn.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54565 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'array.c')
-rw-r--r-- | array.c | 87 |
1 files changed, 87 insertions, 0 deletions
@@ -5651,6 +5651,92 @@ rb_ary_dig(int argc, VALUE *argv, VALUE self) } /* + * call-seq: + * ary.sum -> number + * + * Returns the sum of elements. + * For example, [e1, e2, e3].sum returns 0 + e1 + e2 + e3. + * + * If <i>ary</i> is empty, it returns 0. + * + * [].sum #=> 0 + * [1, 2, 3].sum #=> 6 + * [3, 5.5].sum #=> 8.5 + * + * This method may not respect method redefinition of "+" methods + * such as Fixnum#+. + * + */ + +VALUE +rb_ary_sum(VALUE ary) +{ + VALUE v, e; + long i, n; + + if (RARRAY_LEN(ary) == 0) + return LONG2FIX(0); + + v = LONG2FIX(0); + + n = 0; + for (i = 0; i < RARRAY_LEN(ary); i++) { + e = RARRAY_AREF(ary, i); + if (FIXNUM_P(e)) { + n += FIX2LONG(e); /* should not overflow long type */ + if (!FIXABLE(n)) { + v = rb_big_plus(LONG2NUM(n), v); + n = 0; + } + } + else if (RB_TYPE_P(e, T_BIGNUM)) + v = rb_big_plus(e, v); + else + goto not_integer; + } + if (n != 0) + v = rb_fix_plus(LONG2FIX(n), v); + return v; + + not_integer: + if (n != 0) + v = rb_fix_plus(LONG2FIX(n), v); + + if (RB_FLOAT_TYPE_P(e)) { + /* Kahan's compensated summation algorithm */ + double f, c; + f = NUM2DBL(v); + c = 0.0; + for (; i < RARRAY_LEN(ary); i++) { + double x, y, t; + e = RARRAY_AREF(ary, i); + if (RB_FLOAT_TYPE_P(e)) + x = RFLOAT_VALUE(e); + else if (FIXNUM_P(e)) + x = FIX2LONG(e); + else if (RB_TYPE_P(e, T_BIGNUM)) + x = rb_big2dbl(e); + else + goto not_float; + + y = x - c; + t = f + y; + c = (t - f) - y; + f = t; + } + return DBL2NUM(f); + + not_float: + v = DBL2NUM(f); + } + + for (; i < RARRAY_LEN(ary); i++) { + v = rb_funcall(v, idPLUS, 1, RARRAY_AREF(ary, i)); + } + return v; +} + +/* * Arrays are ordered, integer-indexed collections of any object. * * Array indexing starts at 0, as in C or Java. A negative index is assumed @@ -6005,6 +6091,7 @@ Init_Array(void) rb_define_method(rb_cArray, "bsearch_index", rb_ary_bsearch_index, 0); rb_define_method(rb_cArray, "any?", rb_ary_any_p, 0); rb_define_method(rb_cArray, "dig", rb_ary_dig, -1); + rb_define_method(rb_cArray, "sum", rb_ary_sum, 0); id_cmp = rb_intern("<=>"); id_random = rb_intern("random"); |