Tonix517 commented on a change in pull request #24994: [SPARK-28133] Adding
inverse hyperbolic functions in SQL
URL: https://github.com/apache/spark/pull/24994#discussion_r298813645
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/mathExpressions.scala
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@@ -557,6 +578,27 @@ case class Sin(child: Expression) extends
UnaryMathExpression(math.sin, "SIN")
""")
case class Sinh(child: Expression) extends UnaryMathExpression(math.sinh,
"SINH")
+@ExpressionDescription(
+ usage = """
+ _FUNC_(expr) - Returns inverse hyperbolic sine of `expr`.
+ """,
+ arguments = """
+ Arguments:
+ * expr - hyperbolic angle
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_(0);
+ 0.0
+ """)
+case class Asinh(child: Expression)
+ extends UnaryMathExpression((x: Double) => math.log(x + math.sqrt(x * x +
1.0)), "ASINH") {
+ override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+ defineCodeGen(ctx, ev, c =>
+ s"${ev.value} = java.lang.Math.log($c + java.lang.Math.sqrt($c * $c +
1.0));")
Review comment:
took a closer look at asinh\atanh implementation in FastMath. the negative
handling inside is to apply calculation optimization on abs(double a) and then
apply proper sign at the end of the function to return, which should produce
the same value as the original formula i'm using here
(https://en.wikipedia.org/wiki/Inverse_hyperbolic_functions#Definitions_in_terms_of_logarithms).
But FastMath runs faster than the original functions though.
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