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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2020/08/05 05:42:14 UTC
[GitHub] [arrow] emkornfield commented on a change in pull request #7885: ARROW-9640: [C++][Gandiva] Implement round() for integers and long integers
emkornfield commented on a change in pull request #7885:
URL: https://github.com/apache/arrow/pull/7885#discussion_r465485532
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File path: cpp/src/gandiva/precompiled/arithmetic_ops.cc
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@@ -234,6 +234,25 @@ DIV_FLOAT(float64)
#undef DIV_FLOAT
+#define ROUND(TYPE) \
+ FORCE_INLINE \
+ gdv_##TYPE round_##TYPE(gdv_##TYPE number, gdv_int32 place) { \
+ if (number == 0) { \
+ return 0; \
+ } \
+ if (number < 0) { \
+ return -round_##TYPE(-number, place); \
+ } \
+ return floor(number * pow(10, place) + 0.5) * pow(10, -place); \
Review comment:
My suggestion would be to avoid floating point operations altogether. I haven't tested this but for pow(10, ...) on integers I think either a lookup table or recursive/squaring would like be more efficient. Then for rounding I think something like:
(num + (pow(10, -(precision + 1)) * 5) / pow(10, -precision) should work.
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