mihaibudiu commented on code in PR #3689:
URL: https://github.com/apache/calcite/pull/3689#discussion_r1494967077
##########
core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
##########
@@ -2788,6 +2788,18 @@ public static double log(BigDecimal d0, BigDecimal d1) {
return Math.log(d0.doubleValue()) / Math.log(d1.doubleValue());
}
+ /** SQL {@code LOG2(number)} function applied to double values. */
+ public static double log2(double d0) {
+ return (d0 == 0) ? Double.NaN : Math.log(d0) / Math.log(2);
+ }
+
+ /** SQL {@code LOG2(number)} function applied to
+ * BigDecimal and double values. */
+ public static double log2(BigDecimal d0) {
+ return (d0.doubleValue() == 0) ? Double.NaN : Math.log(d0.doubleValue()) /
Math.log(2);
Review Comment:
just call the other function.
##########
testkit/src/main/java/org/apache/calcite/test/SqlOperatorTest.java:
##########
@@ -6222,6 +6222,41 @@ void checkRegexpExtract(SqlOperatorFixture f0,
FunctionAlias functionAlias) {
f.checkNull("log(10, cast(null as real))");
}
+
+ /** Test case for
+ * <a
href="https://issues.apache.org/jira/browse/CALCITE-6224";>[CALCITE-6224]
+ * Add LOG2 function (enabled in MYSQL, Spark library)</a>. */
+ @Test void testLog2Func() {
+ final SqlOperatorFixture f0 = fixture();
+ f0.checkFails("^log2(4)^",
+ "No match found for function signature LOG2\\(<NUMERIC>\\)", false);
+ final Consumer<SqlOperatorFixture> consumer = f -> {
+ f.setFor(SqlLibraryOperators.LOG2);
+ f.checkScalarApprox("log2(2)", "DOUBLE NOT NULL",
+ isWithin(1.0, 0.000001));
+ f.checkScalarApprox("log2(4)", "DOUBLE NOT NULL",
+ isWithin(2.0, 0.000001));
+ f.checkScalarApprox("log2(65536)", "DOUBLE NOT NULL",
+ isWithin(16.0, 0.000001));
+ f.checkScalarApprox("log2(2.0/3)", "DOUBLE NOT NULL",
+ isWithin(-0.5849625007211561, 0.000001));
+ f.checkScalarApprox("log2(4.0/3)", "DOUBLE NOT NULL",
+ isWithin(0.4150374992788435, 0.000001));
+ f.checkScalarApprox("log2(0.5)", "DOUBLE NOT NULL",
+ isWithin(-1.0, 0.000001));
+ f.checkScalarApprox("log2(cast(10e8 as double))", "DOUBLE NOT NULL",
+ isWithin(29.897352853986263, 0.000001));
+ f.checkScalarApprox("log2(cast(10e8 as float))", "DOUBLE NOT NULL",
+ isWithin(29.897352853986263, 0.000001));
+ f.checkScalarApprox("log2(-2)", "DOUBLE NOT NULL",
+ "NaN");
+ f.checkScalarApprox("log2(0)", "DOUBLE NOT NULL",
+ "NaN");
+ f.checkNull("log2(cast(null as real))");
Review Comment:
how about a test with just NULL, without the cast? that should work.
##########
core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
##########
@@ -2788,6 +2788,18 @@ public static double log(BigDecimal d0, BigDecimal d1) {
return Math.log(d0.doubleValue()) / Math.log(d1.doubleValue());
}
+ /** SQL {@code LOG2(number)} function applied to double values. */
+ public static double log2(double d0) {
+ return (d0 == 0) ? Double.NaN : Math.log(d0) / Math.log(2);
Review Comment:
In general testing for equality FP values does not work.
There are also two kinds of zeros in FP, +0 and -0.
If the result from Math.log(0) is -Infinity, the more robust way to do this
is to actually compute the log and check when the result is the negative
infinity.
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