rok commented on a change in pull request #9841:
URL: https://github.com/apache/arrow/pull/9841#discussion_r605671752
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File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
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@@ -233,6 +235,282 @@ struct DivideChecked {
}
};
+struct Power {
+ template <typename T, typename Arg0, typename Arg1>
+ static enable_if_signed_integer<T> Call(KernelContext* ctx, Arg0 left, Arg1
right) {
+ Arg0 result = 1;
+ if (left == 0) {
+ if (right < 0) {
+ ARROW_PREDICT_FALSE(MultiplyWithOverflow(2,
std::numeric_limits<Arg0>::max(), &result));
+ ctx->SetStatus(Status::Invalid("divide by zero"));
+ return result;
+ } else if (right == 0) {
+ return 1;
+ }
+ return 0;
+ } else if (right == INFINITY && abs(left) > 1) {
+ ARROW_PREDICT_FALSE(MultiplyWithOverflow(2,
std::numeric_limits<Arg0>::max(), &result));
+ return result;
+ } else if (right == -INFINITY && abs(left) > 1) {
+ return 0;
+ }
+
+ if (right > 0) {
+ for (Arg1 i = 0; i < right; i++) {
+ if (ARROW_PREDICT_FALSE(MultiplyWithOverflow(result, left, &result))) {
+ ctx->SetStatus(Status::Invalid("overflow"));
+ }
+ }
+ } else {
+ for (Arg1 i = 0; i < -right; i++) {
Review comment:
Good point @jorisvandenbossche.
So from users perspective negative exponents will return integer rounded
results which is not bad if it doesn't surprise the user. But the user might
want to go from integers to floats without converting the input first.
Shall we keep the current kernels and add an option to return floats from
ints when requested? Or should it be an opt out?
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