Re: Possible error in bc

[Hans-Bernhard Broeker]

Harald Anlauf <address@hidden> wrote:
> address@hidden (Dean Allen Provins) writes:

>> It was my understanding (and I checked my CRC math tables book, and
>> also tried gcc in a simple test) that 0^0 should be 0 (zero).

> I don't know how you fouled gcc into this, but this is clearly wrong.

"Wrong" is bit strong.  0^0 is mathematically an undefined operation,
which can easily be seen from some approaches to computing it:

        (any other number but 0)^0 = 1
        0^(any positive number) = 0
        0^(any negative number) = infinity (or undefined, your choice)

So: which is it going to be?  Both 0 and 1 are commonly assumed in
some areas of mathematics.

And neither do you have to fould GCC to give such a result.  That's
entirely within the freedom of the C *library* implementor do decide
what the result is: The result of pow(0,0) is implementation-defined,
and it's not up to GCC to decide what it may be.  Or did you assume he
actually wrote 0^0?  Which in C means an exclusive OR operation, and
should return 0.
-- 
Hans-Bernhard Broeker (address@hidden)
Even if all the snow were burnt, ashes would remain.