Details

Type: Defect

Status: Reopened

Priority: Trivial

Resolution: Unresolved

Affects Version/s: None

Fix Version/s: None

Component/s: None

Labels:

Patch:Code and Test

Approval:Prescreened
Description
Would expect both of these to return NaN but first does not:
user=> (def x Double/NaN) #'user/x user=> (/ x 0) ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156) user=> (/ Double/NaN 0) Double/NaN
Cause: Here we are dividing a double by a long. In the first case, this is parsed as divide(Object, long) which then calls divide(Object, Object), which throws ArithmeticException if the second arg is 0 (regardless of the first arg).
In the second case it's parsed as divide(double, long) which just relies on Java to properly upcast the primitive long to a double to do the divide.
Note that making this call with 2 doubles does return NaN:
user=> (def x Double/NaN)
#'user/x
user=> (/ x 0.0)
NaN
or type hinting x to a double works as well:
user=> (def x Double/NaN) #'user/x user=> (/ ^double x 0.0) NaN
Proposed: Add checks in divide(Object, Object) to check whether x is NaN and instead return NaN.
Patch: fixclj1371.patch
Prescreened by: Alex Miller
Attachments
Activity
Alex Miller
made changes 
Field  Original Value  New Value 

Status  Open [ 1 ]  Closed [ 6 ] 
Resolution  Declined [ 2 ] 
Alex Miller
made changes 
Resolution  Declined [ 2 ]  
Status  Closed [ 6 ]  Reopened [ 4 ] 
Alex Miller
made changes 
Priority  Major [ 3 ]  Trivial [ 5 ] 
Alex Miller
made changes 
Labels  math 
Alex Miller
made changes 
Summary  Weird NaN behavior  divide(Object, Object) with (NaN, 0) does not return NaN 
Pavlos Vinieratos
made changes 
Attachment  fixclj1371.patch [ 16028 ] 
Alex Miller
made changes 
Priority  Trivial [ 5 ]  Minor [ 4 ] 
Approval  Prescreened [ 10220 ]  
Patch  Code and Test [ 10002 ] 
Alex Miller
made changes 
Description 
user=> (def x Double/NaN)
#'user/x user=> (/ x 0) ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156) user=> (/ Double/NaN 0) Double/NaN 
{code}
user=> (def x Double/NaN) #'user/x user=> (/ x 0) ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156) user=> (/ Double/NaN 0) Double/NaN {code} *Cause:* Here we are dividing a double by a long. In the first case, this is parsed as divide(Object, long) which then calls divide(Object, Object), which throws ArithmeticException if the second arg is 0 (regardless of the first arg). In the second case it's parsed as divide(double, long) which just relies on Java to properly upcast the primitive long to a double to do the divide. Note that making this call with 2 doubles does return NaN: {code} user=> (def x Double/NaN) #'user/x user=> (/ x 0.0) NaN {code} or type hinting x to a double works as well: {code} user=> (def x Double/NaN) #'user/x user=> (/ ^double x 0.0) NaN {code} *Proposed:* Add checks in divide(Object, Object) to check whether x is NaN and instead return NaN. *Patch:* fixclj1371.patch *Prescreened by:* Alex Miller 
Alex Miller
made changes 
Priority  Minor [ 4 ]  Trivial [ 5 ] 
Description 
{code}
user=> (def x Double/NaN) #'user/x user=> (/ x 0) ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156) user=> (/ Double/NaN 0) Double/NaN {code} *Cause:* Here we are dividing a double by a long. In the first case, this is parsed as divide(Object, long) which then calls divide(Object, Object), which throws ArithmeticException if the second arg is 0 (regardless of the first arg). In the second case it's parsed as divide(double, long) which just relies on Java to properly upcast the primitive long to a double to do the divide. Note that making this call with 2 doubles does return NaN: {code} user=> (def x Double/NaN) #'user/x user=> (/ x 0.0) NaN {code} or type hinting x to a double works as well: {code} user=> (def x Double/NaN) #'user/x user=> (/ ^double x 0.0) NaN {code} *Proposed:* Add checks in divide(Object, Object) to check whether x is NaN and instead return NaN. *Patch:* fixclj1371.patch *Prescreened by:* Alex Miller 
Would expect both of these to return NaN but first does not:
{code} user=> (def x Double/NaN) #'user/x user=> (/ x 0) ArithmeticException Divide by zero clojure.lang.Numbers.divide (Numbers.java:156) user=> (/ Double/NaN 0) Double/NaN {code} *Cause:* Here we are dividing a double by a long. In the first case, this is parsed as divide(Object, long) which then calls divide(Object, Object), which throws ArithmeticException if the second arg is 0 (regardless of the first arg). In the second case it's parsed as divide(double, long) which just relies on Java to properly upcast the primitive long to a double to do the divide. Note that making this call with 2 doubles does return NaN: {code} user=> (def x Double/NaN) #'user/x user=> (/ x 0.0) NaN {code} or type hinting x to a double works as well: {code} user=> (def x Double/NaN) #'user/x user=> (/ ^double x 0.0) NaN {code} *Proposed:* Add checks in divide(Object, Object) to check whether x is NaN and instead return NaN. *Patch:* fixclj1371.patch *Prescreened by:* Alex Miller 