fix: allow inf for get_rank

Author: proost

tdigest/include/tdigest.hpp

@@ -154,7 +154,6 @@ class tdigest {
    * Compute approximate normalized rank of the given value.
    *
    * <p>If the sketch is empty this throws std::runtime_error.
-   * <p>NaN and infinity values throw std::invalid_argument.
    *
    * @param value to be ranked
    * @return normalized rank (from 0 to 1 inclusive)

tdigest/include/tdigest_impl.hpp

@@ -109,7 +109,6 @@ template<typename T, typename A>
 double tdigest<T, A>::get_rank(T value) const {
   if (is_empty()) throw std::runtime_error("operation is undefined for an empty sketch");
   if (std::isnan(value)) throw std::invalid_argument("operation is undefined for NaN");
-  if (std::isinf(value)) throw std::invalid_argument("operation is undefined for infinity");
   if (value < min_) return 0;
   if (value > max_) return 1;
   // one centroid and value == min_ == max_

tdigest/test/tdigest_test.cpp

@@ -510,20 +510,6 @@ TEST_CASE("update rejects negative infinity", "[tdigest]") {
   REQUIRE(td.get_min_value() == 1.0);
 }
 
-TEST_CASE("get_rank rejects positive infinity", "[tdigest]") {
-  tdigest_double td(100);
-  td.update(1.0);
-  td.update(2.0);
-  REQUIRE_THROWS_AS(td.get_rank(std::numeric_limits<double>::infinity()), std::invalid_argument);
-}
-
-TEST_CASE("get_rank rejects negative infinity", "[tdigest]") {
-  tdigest_double td(100);
-  td.update(1.0);
-  td.update(2.0);
-  REQUIRE_THROWS_AS(td.get_rank(-std::numeric_limits<double>::infinity()), std::invalid_argument);
-}
-
 TEST_CASE("deserialize bytes rejects NaN single value", "[tdigest]") {
   tdigest_double td(100);
   td.update(1.0);