Hello everyone!
I want to start the discussion on the RFC: Raising zero to the power of
negative number
Link: https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number
Kind regards,
Jorg
Hello everyone!
I want to start the discussion on the RFC: Raising zero to the power of
negative numberLink: https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number
Kind regards,
Jorg
In Python, the error message for 0 ** -1 is:
ZeroDivisionError: 0.0 cannot be raised to a negative power
Instead of "DivisionByZeroError: Division by zero" as the PHP exception
message, could we use a similar message? Something like:
DivisionByZeroError: Zero cannot be raised to a negative power
I think this will be clearer to a user who encounters this error and
isn't aware that raising zero to a negative power is the equivalent of
dividing by zero.
Cheers,
Ben
Hello everyone!
I want to start the discussion on the RFC: Raising zero to the power of
negative numberLink: https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number
Kind regards,
Jorg
IEEE 754 dictates that an infinity should be the expected output for all
these scenarios.
Hello everyone!
I want to start the discussion on the RFC: Raising zero to the power of
negative numberLink: https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number
Kind regards,
JorgIEEE 754 dictates that an infinity should be the expected output for all
these scenarios.
If I'm reading the text of IEEE 754-2019 correctly, it means that the
division by zero error should occur when an operation on finite operands
gives an exact infinite result.
"The divideByZero exception shall be signaled if and only if an exact
infinite result is defined for an operation on finite operands."
Cheers,
Ben
Hello everyone!
I want to start the discussion on the RFC: Raising zero to the power of
negative numberLink: https://wiki.php.net/rfc/raising_zero_to_power_of_negative_number
Kind regards,
JorgIEEE 754 dictates that an infinity should be the expected output for all
these scenarios.
IEEE 754 only deals with floating point numbers, and even then if you want IEEE 754 behaviour for division you need to use fdiv() as of PHP 8.0 as any division by 0 throws this error since https://wiki.php.net/rfc/engine_warnings#division_by_zero got accepted.
I think this change makes sense but would rather have an improved wording/Error as proposed by Ben.
Best regards,
Gina P. Banyard
Thank you for the suggestions. I agree that error message should be more
meaningful. I changed it.
The main driver of this change is to match the division by zero behavior
for both operators which can operate on both integers and floats. Would it
make sense to create a function fpow similarly to fdiv for the correct
IEEE 754 logic?
Kind regards,
Jorg
Hello everyone,
If there is no other feedback I would like to start voting in the next few
days.
Kind regards,
Jorg
Hi Jorg,
Thank you for the suggestions. I agree that error message should be more
meaningful. I changed it.The main driver of this change is to match the division by zero behavior
for both operators which can operate on both integers and floats. Would it
make sense to create a functionfpowsimilarly tofdivfor the correct
IEEE 754 logic?
As of your note of consistent behavior here, in your RFC I don't see any
note about operating on float - It's all about int. It would be good to
explicitly describe both int and float behavior in your RFC.
About fpow - I personally never felled the need to use fdiv but as
fdiv was explicitly introduced to expose IEEE-754 semantics I think it
totally makes sense to add fpow as well.
Greetings,
Marc
Kind regards,
Jorg
Thank you Marc for your opinion. It makes sense to me that we should have
the possibility to mimic the IEEE-754 standard, thus we should have fpow
function as well. I have updated the RFC and would like to start the voting
if there are no new comments.
Kind regards,
Jorg Sowa