[GitHub] [arrow] lidavidm commented on a change in pull request #10567: ARROW-13096: [C++] Implement logarithm compute functions

[GitBox <gi...@apache.org>]

lidavidm commented on a change in pull request #10567:
URL: https://github.com/apache/arrow/pull/10567#discussion_r662455707



##########
File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
##########
@@ -686,6 +686,118 @@ struct Atan2 {
   }
 };
 
+struct LogNatural {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status*) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0.0) {
+      return -std::numeric_limits<T>::infinity();
+    } else if (arg < 0.0) {
+      return std::numeric_limits<T>::quiet_NaN();
+    }
+    return std::log(arg);
+  }
+};
+
+struct LogNaturalChecked {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status* st) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0.0) {
+      *st = Status::Invalid("divide by zero");
+      return arg;
+    } else if (arg < 0.0) {
+      *st = Status::Invalid("domain error");
+      return arg;
+    }
+    return std::log(arg);
+  }
+};
+
+struct Log10 {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status*) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0.0) {
+      return -std::numeric_limits<T>::infinity();
+    } else if (arg < 0.0) {
+      return std::numeric_limits<T>::quiet_NaN();
+    }
+    return std::log10(arg);
+  }
+};
+
+struct Log10Checked {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status* st) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0) {
+      *st = Status::Invalid("divide by zero");
+      return arg;
+    } else if (arg < 0) {
+      *st = Status::Invalid("domain error");
+      return arg;
+    }
+    return std::log10(arg);
+  }
+};
+
+struct Log2 {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status*) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0.0) {
+      return -std::numeric_limits<T>::infinity();
+    } else if (arg < 0.0) {
+      return std::numeric_limits<T>::quiet_NaN();
+    }
+    return std::log2(arg);
+  }
+};
+
+struct Log2Checked {
+  template <typename T, typename Arg>
+  static enable_if_floating_point<Arg, T> Call(KernelContext*, Arg arg, Status* st) {
+    static_assert(std::is_same<T, Arg>::value, "");
+    if (arg == 0.0) {
+      *st = Status::Invalid("divide by zero");
+      return arg;
+    } else if (arg < 0.0) {
+      *st = Status::Invalid("domain error");
+      return arg;
+    }
+    return std::log2(arg);
+  }
+};

Review comment:
       I could make it templated on two functions (one for float, one for double)?




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