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https://issues.apache.org/jira/browse/SPARK-28519?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen updated SPARK-28519:
------------------------------
Docs Text:
The result of `java.lang.Math`'s `log`, `log1p`, `exp`, `expm1`, and `pow` may
vary across platforms. In Spark 3.0, the result of the equivalent SQL functions
(including related SQL functions like `LOG10`) return values consistent with
`java.lang.StrictMath`. In virtually all cases this makes no difference in the
return value, and the difference is very small, but may not exactly match
`java.lang.Math` on x86 platforms in cases like, for example, `log(3.0)`, whose
value varies between `Math.log()` and `StrictMath.log()`.
was:The result of the JVM's Math.log and Math.pow may vary across platforms.
In Spark 3.0, the result of SQL functions related to log() and pow() return
values consistent with StrictMath.log() and StrictMath.pow(). In virtually all
cases this makes no difference in the return value, and the difference is very
small, but may not exactly match Math.log() and Math.pow() in cases like,
notably, log(3.0), whose value varies between Math.log() and StrictMath.log().
> Tests failed on aarch64 due the value of math.log and power function is
> different
> ---------------------------------------------------------------------------------
>
> Key: SPARK-28519
> URL: https://issues.apache.org/jira/browse/SPARK-28519
> Project: Spark
> Issue Type: Test
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: huangtianhua
> Priority: Major
> Labels: release-notes
>
> Sorry to disturb again, we ran unit tests on arm64 instance, and there are
> other sql tests failed:
> {code}
> - pgSQL/float8.sql *** FAILED ***
> Expected "{color:#f691b2}0.549306144334054[9]{color}", but got
> "{color:#f691b2}0.549306144334054[8]{color}" Result did not match for query
> #56
> SELECT atanh(double('0.5')) (SQLQueryTestSuite.scala:362)
> - pgSQL/numeric.sql *** FAILED ***
> Expected "2 {color:#59afe1}2247902679199174[72{color}
> 224790267919917955.1326161858
> 4 7405685069595001 7405685069594999.0773399947
> 5 5068226527.321263 5068226527.3212726541
> 6 281839893606.99365 281839893606.9937234336
> 7 {color:#d04437}1716699575118595840{color} 1716699575118597095.4233081991
> 8 167361463828.0749 167361463828.0749132007
> 9 {color:#14892c}107511333880051856]{color} 107511333880052007....", but got
> "2 {color:#59afe1}2247902679199174[40{color} 224790267919917955.1326161858
> 4 7405685069595001 7405685069594999.0773399947
> 5 5068226527.321263 5068226527.3212726541
> 6 281839893606.99365 281839893606.9937234336
> 7 {color:#d04437}1716699575118595580{color} 1716699575118597095.4233081991
> 8 167361463828.0749 167361463828.0749132007
> 9 {color:#14892c}107511333880051872]{color} 107511333880052007...." Result
> did not match for query #496
> SELECT t1.id1, t1.result, t2.expected
> FROM num_result t1, num_exp_power_10_ln t2
> WHERE t1.id1 = t2.id
> AND t1.result != t2.expected (SQLQueryTestSuite.scala:362)
> {code}
> The first test failed, because the value of math.log(3.0) is different on
> aarch64:
> # on x86_64:
> {code}
> scala> math.log(3.0)
> res50: Double = 1.0986122886681098
> {code}
> # on aarch64:
> {code}
> scala> math.log(3.0)
> res19: Double = 1.0986122886681096
> {code}
> And I tried {{math.log(4.0)}}, {{math.log(5.0)}} and they are same, I don't
> know why {{math.log(3.0)}} is so special? But the result is different indeed
> on aarch64.
> The second test failed, because some values of pow() is different on aarch64,
> according to the test, I took tests on aarch64 and x86_64, take '-83028485'
> as example:
> # on x86_64:
> {code}
> scala> import java.lang.Math._
> import java.lang.Math._
> scala> abs(-83028485)
> res3: Int = 83028485
> scala> var a = -83028485
> a: Int = -83028485
> scala> abs(a)
> res4: Int = 83028485
> scala> math.log(abs(a))
> res5: Double = 18.234694299654787
> scala> pow(10, math.log(abs(a)))
> res6: Double ={color:#d04437} 1.71669957511859584E18{color}
> {code}
> # on aarch64:
> {code}
> scala> var a = -83028485
> a: Int = -83028485
> scala> abs(a)
> res38: Int = 83028485
> scala> math.log(abs(a))
> res39: Double = 18.234694299654787
> scala> pow(10, math.log(abs(a)))
> res40: Double = 1.71669957511859558E18
> {code}
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