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How would you prepare for javascripting interview?

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  How would you prepare for javascripting interview? justaguy <lichunshen84@gmail.com> - 2016-07-18 09:10 -0700
    Re: How would you prepare for javascripting interview? Hans-Georg Michna <hans-georgNoEmailPlease@michna.com> - 2016-07-18 18:37 +0200
      Re: How would you prepare for javascripting interview? justaguy <lichunshen84@gmail.com> - 2016-07-18 11:09 -0700
        Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-07-21 01:04 +0000
          Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-07-21 14:24 +0100
          Re: How would you prepare for javascripting interview? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-07-23 16:25 +0200
            Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-07-23 15:56 +0000
              Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-03 19:39 +0000
                Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-04 15:56 +0000
                  Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-05 00:06 +0100
                    Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-05 14:49 +0100
                      Re: How would you prepare for javascripting interview? $Bill <news@todbe.com> - 2016-09-05 10:01 -0700
                      Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-06 09:36 -0700
                    Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-05 15:05 +0100
                      Re: How would you prepare for javascripting interview? Andreas Bergmaier <andber93@web.de> - 2016-09-05 20:31 +0200
                        Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-06 15:15 +0000
                        Re: How would you prepare for javascripting interview? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-09-06 19:40 +0200
                        Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-06 19:25 +0100
                          Re: How would you prepare for javascripting interview? Andreas Bergmaier <andber93@web.de> - 2016-09-06 22:16 +0200
                            Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-07 17:17 +0100
                              Re: How would you prepare for javascripting interview? Andreas Bergmaier <andber93@web.de> - 2016-09-07 20:07 +0200
                            Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-08 14:36 +0100
                      Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-05 18:46 +0000
                        Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-05 20:32 +0100
                    Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-05 17:27 +0000
                      Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-05 20:12 +0100
                        Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-06 16:48 +0000
                          Re: How would you prepare for javascripting interview? Andreas Bergmaier <andber93@web.de> - 2016-09-06 19:56 +0200
                            Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-07 20:16 +0000
                          Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-07 10:01 -0700
                            Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-07 20:21 +0000
                              Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-09 11:41 -0700
                                Re: How would you prepare for javascripting interview? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2016-09-09 15:35 -0700
                                  Re: How would you prepare for javascripting interview? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2016-09-09 20:40 -0700
                                Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-10 15:12 +0000
                                  Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-12 11:14 -0700
                                    Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-13 21:07 +0000
                      Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-06 16:20 +0000
                    Re: How would you prepare for javascripting interview? Ken Tilton <kentilton@gmail.com> - 2016-09-05 11:37 -0700
                    Re: How would you prepare for javascripting interview? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-09-06 19:26 +0200
                    Re: How would you prepare for javascripting interview? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2016-09-08 12:41 -0700
                  Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-05 20:37 +0000
                    Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-05 22:13 +0100
                      Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-06 02:33 +0000
                    Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-06 16:02 +0000
                      Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-06 09:50 -0700
                        Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-07 01:36 +0000
                          Re: How would you prepare for javascripting interview? Gene Wirchenko <genew@telus.net> - 2016-09-07 10:07 -0700
                            Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-10 00:03 +0000
                              Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-10 00:12 +0000
                              Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-10 15:34 +0000
                                Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-11 01:32 +0100
                                  Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-12 19:26 +0000
                                    Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-13 01:02 +0100
                                      Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-13 21:38 +0000
                                        Re: How would you prepare for javascripting interview? "Christoph M. Becker" <cmbecker69@arcor.de> - 2016-09-14 00:56 +0200
                                          Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-15 15:09 +0000
                                        Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-14 00:47 +0100
                                          Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-15 15:34 +0000
                                Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-11 02:45 +0000
                                  Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-12 19:10 +0000
                                    Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-12 21:06 +0100
                      Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-07 03:12 +0000
                        Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-07 19:53 +0000
                          Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-10 02:14 +0000
                            Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-10 11:25 +0100
                              Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-10 15:49 +0100
                            Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-10 18:39 +0000
                              Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-11 02:45 +0000
                                Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-11 16:23 +0100
                                  Re: How would you prepare for javascripting interview? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-12 20:32 +0100
                                Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-12 18:49 +0000
                                  Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-13 00:27 +0000
                                    Re: How would you prepare for javascripting interview? Tim Streater <timstreater@greenbee.net> - 2016-09-13 08:51 +0100
                                      Re: How would you prepare for javascripting interview? Jon Ribbens <jon+usenet@unequivocal.eu> - 2016-09-13 12:33 +0000
                                      Re: How would you prepare for javascripting interview? Scott Sauyet <scott@sauyet.com> - 2016-09-14 01:17 +0000
                                        Re: How would you prepare for javascripting interview? Tim Streater <timstreater@greenbee.net> - 2016-09-14 11:15 +0100
                                        Re: How would you prepare for javascripting interview? Doc O'Leary  <droleary@2015usenet1.subsume.com> - 2016-09-15 15:02 +0000
                                  Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-13 10:06 +0100
                    Re: How would you prepare for javascripting interview? John Harris <niam@jghnorth.org.uk.invalid> - 2016-09-06 19:53 +0100
      Re: How would you prepare for javascripting interview? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-07-18 22:30 +0200
    Re: How would you prepare for javascripting interview? justaguy <lichunshen84@gmail.com> - 2016-07-18 14:56 -0700
    Re: How would you prepare for javascripting interview? Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2016-07-19 16:01 -0300
      Re: How would you prepare for javascripting interview? Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2016-07-19 16:16 -0300

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#31270

John Harris wrote:

>> If I had to implement this, I would use the `max` function on
>> non-negative integers (the type of path lengths), whose identity element
>> is 0. It would then read
>>
>>   MaxPathLen(t) = max(MathPathLen(c) + 1 foreach c of the children of t)
>   <snip>
>
> That's a third way to specify the function, but max() is still
> "custom-built for the arbitrary requirements" :-D

Nah, I used the very generic `maximum` function that you snipped away :-D

> Concerning identity elements, can you explain their possible
> significance here. To me, an identity element, e, is defined by
>   x op e = x
> not by
>     op e = e
> (no x), or
>     op   = e
> (no anything).

Yes. In the case where `op` is the maximum of two floating point 
numbers, we have
   Math.max(x, -Infinity) == x
(and
   Math.max(-Infinity, x) == x
because it's commutative)

Only if we have a variadic function, or - if properly typed - one that 
takes a list/set/collection of elements, it does become significant.
We would define

function max(a, b) {
     return a > b ? a : b;
}
function maximum(args) {
     if (args.length == 0)
         return -Infinity;
     else
         return max(args[0], maximum(args.slice(1)));
}
Math.max = function(...args) { return maximum(args) };
// or simply
Math.max = function(...args) { return args.reduce(max, -Infinity); };

- Bergi

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#31278

On Tue, 6 Sep 2016 22:16:23 +0200, Andreas Bergmaier <andber93@web.de>
wrote:

>John Harris wrote:
>
>> A
>> Given any node t
>>   if   t is a leaf node
>>   then MaxPathLen(t) = 0
>>   else MaxPathLen(t) = 1 + max(MaxPathLen(c) of the children, c, of t)
>>
>> B
>> Given any node t
>>   MaxPathLen(t) = 1 + max(MaxPathLen(c) of the children, c, of t)
>> Specify and implement max so that max() = -1
>>
>> Version A carefully avoids the max() horror.
>
>Which is quite sensible and makes the code more readable to most of us. 
>"Leaf" and "Node", in many tree implementations represented by different 
>classes, are two separate cases to be handled, and the primitive 
>recursion pattern is obvious in this phrasing of the algorithm.
>
>> Version B uses a max function carefully tuned to the needs of this
>> kind of use.
>
>"Carefully tuned" seems to mean "custom-built for the arbitrary 
>requirements" :-D
>If I had to implement this, I would use the `max` function on 
>non-negative integers (the type of path lengths), whose identity element 
>is 0. It would then read
>
>   MaxPathLen(t) = max(MathPathLen(c) + 1 foreach c of the children of t)

It now occurs to me that there is yet another specification of
MaxPathLen that has a different way of using max, a way that nullifies
all arguments about identity values and arbitrary values.

Instead of writing 
  max(), max(a), max(a, b), max(a, b, c), ...  
write
  max(z), max(z, a), max(z, a, b), max(z, a, b, c), ...  
where z is your favourite identity value or required arbitrary value.
Then I would write

Given any node t 
  MaxPathLen(t) = 1 + max(-1, MaxPathLen(c) of the children, c, of t)

and you would write

  MaxPathLen(t) 
  = max(0, MathPathLen(c) + 1 foreach c of the children of t)

Then in an ECMAScript program a result of -infinity would indicate a
serious programming error.

  John

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#31240

John Harris wrote:

> For your next problem, what should max be when given an infinite
> collection of different numbers? It can't be a finite number because
> that would be less than some of the numbers in the collection. It can't
> be an infinite number because that would be bigger than any of the
> numbers in the collection.

Well, it's easy enough to imagine an infinite collection, say, of all the 
positive rational numbers whose squares are less than 2.  There's an 
obvious finite maximum in the real numbers, sqrt(2).  See Dedekind cuts 
for more information.  [1]

But none of this has to do with programming.  This is the realm of pure 
mathematics now.

  [1]: E.g.: <https://en.wikipedia.org/wiki/Dedekind_cut>

  -- Scott

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#31243

ram@zedat.fu-berlin.de (Stefan Ram) writes:

> Scott Sauyet <scott@sauyet.com> writes:
>>Well, it's easy enough to imagine an infinite collection, say, of all the 
>>positive rational numbers whose squares are less than 2.  There's an 
>>obvious finite maximum in the real numbers, sqrt(2).  See Dedekind cuts 
>>for more information.  [1]
>
>   /Supremum/. The /maximum/ of a set is an /element/ of that set,
>   but sqrt(2) is not a number whose square is /less than/ 2.

Curiously, you've been arguing for a definition of maximum where it may
/not/ be an element of the set.

Further, when sup is defined on the extended reals (R U {-oo, +oo}) so
that sup R = oo, it makes sense to define sup {} = -oo (and some authors
actually do this).

So here you seem to arguing that Math.max() = -Infinity is wrong because
the maximum of a set is an element of that set, but there should be a
Math.sup() whose value is -Infinity.

-- 
Ben.

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#31236

For your reference, records indicate that 
Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:

> I don't think anyone is wondering *why* Math.max() = -Infinity so much
> as whether it should be anything at all.

Or, more to the point, why it isn’t defined as something that is 
*conceptually consistent* with other methods for calculating it, 
including how it might be treated for other data types.

For example, if you put the numbers in an array, you might be 
tempted to use something like reduce() to get down to the min/max 
value.  Try that on an empty array and you get a TypeError.  If you 
instead think of it as a sort() followed by an unshift() or pop(), 
trying to do it that way on an empty array returns undefined.

There are probably many other similar *sensible* ways to do the 
operation, and *none* of them will pull an infinity out of nowhere 
like the Math functions do.  It’s an implementation hack that 
should have been fixed as the language matured.  Nobody who defends 
the choice should ever get *any* work in Computer Science, let 
alone a JavaScript job.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31242

Doc O'Leary  <droleary@2015usenet1.subsume.com> writes:

> For your reference, records indicate that 
> Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:
>
>> I don't think anyone is wondering *why* Math.max() = -Infinity so much
>> as whether it should be anything at all.
>
> Or, more to the point, why it isn’t defined as something that is 
> *conceptually consistent* with other methods for calculating it, 
> including how it might be treated for other data types.
>
> For example, if you put the numbers in an array, you might be 
> tempted to use something like reduce() to get down to the min/max 
> value.  Try that on an empty array and you get a TypeError.  If you 
> instead think of it as a sort() followed by an unshift() or pop(), 
> trying to do it that way on an empty array returns undefined.

These are valid points (though you can reduce an empty array provided
you specify the "identity").  But I wonder if you feel the same about:

  > [].every(x=>x)
  true
  > [].some(x=>x)
  false

And would you object to [].sum() being 0 and [].product being 1?  (I
know ECMAScript has neither, I'm just interested in how you see similar
situations.)

> There are probably many other similar *sensible* ways to do the 
> operation, and *none* of them will pull an infinity out of nowhere 
> like the Math functions do.  It’s an implementation hack that 
> should have been fixed as the language matured.  Nobody who defends 
> the choice should ever get *any* work in Computer Science, let 
> alone a JavaScript job.

I was with you up to this point.  The infinity is not pulled out of
nowhere -- there's a reason for it, even if you don't think it's a good
one (or a good enough one).  And even if you disagree with the choice,
it's certainly not a hack, and defending it is no reason be barred from
working with JavaScript.

-- 
Ben.

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#31253

For your reference, records indicate that 
Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:

> Doc O'Leary  <droleary@2015usenet1.subsume.com> writes:
> 
> > For your reference, records indicate that 
> > Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:
> >
> >> I don't think anyone is wondering *why* Math.max() = -Infinity so much
> >> as whether it should be anything at all.
> >
> > Or, more to the point, why it isn’t defined as something that is 
> > *conceptually consistent* with other methods for calculating it, 
> > including how it might be treated for other data types.
> >
> > For example, if you put the numbers in an array, you might be 
> > tempted to use something like reduce() to get down to the min/max 
> > value.  Try that on an empty array and you get a TypeError.  If you 
> > instead think of it as a sort() followed by an unshift() or pop(), 
> > trying to do it that way on an empty array returns undefined.
> 
> These are valid points (though you can reduce an empty array provided
> you specify the "identity").

Yes, you can reduce it to *anything* if you supply that anything!  
We both know the issue is bigger than that.

> But I wonder if you feel the same about:
> 
>   > [].every(x=>x)
>   true
>   > [].some(x=>x)
>   false

I would say there should *definitely* have been a debate on those 
choices as default values, too.  At a higher level, it doesn’t make 
sense to say that something is true for *every* object in a 
collection, but it is *not* true for some of them.

> And would you object to [].sum() being 0 and [].product being 1?  (I
> know ECMAScript has neither, I'm just interested in how you see similar
> situations.)

A sum does essentially start at zero, so I have no objection to that.  
I don’t know any mathematical concept of a product that can similarly 
be said to have a set value.

> I was with you up to this point.  The infinity is not pulled out of
> nowhere -- there's a reason for it, even if you don't think it's a good
> one (or a good enough one).  And even if you disagree with the choice,
> it's certainly not a hack, and defending it is no reason be barred from
> working with JavaScript.

Sorry, but it’s just a dirty hack.  It’s used as the default value 
simply because the implementation makes it a convenient comparison, 
what with *any* value being greater than -Infinity (or the opposite 
for min).  But any actual thought to the *meaning* of the operations 
would lead any competent developer to a different solution, and one 
that provides a sensible result for an empty set *regardless* of the 
type of object that it contains none of.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31257

Doc O'Leary wrote:

> Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:
>
>> But I wonder if you feel the same about:
>>
>>   > [].every(x=>x)
>>   true
>>   > [].some(x=>x)
>>   false
>
> I would say there should *definitely* have been a debate on those
> choices as default values, too.

There's no need for debate. `true` and `false` are the identity values 
for the AND and OR operations.

> At a higher level, it doesn’t make
> sense to say that something is true for *every* object in a
> collection, but it is *not* true for some of them.

Well, you won't find any object in the empty collection for which it is 
not true.
May I refer you to https://en.wikipedia.org/wiki/Vacuous_truth?

>> And would you object to [].sum() being 0 and [].product being 1?  (I
>> know ECMAScript has neither, I'm just interested in how you see similar
>> situations.)
>
> A sum does essentially start at zero, so I have no objection to that.
> I don’t know any mathematical concept of a product that can similarly
> be said to have a set value.

Not knowing about something doesn't imply it would not exist :-) The 
identity element of multiplication is 1.
Have a look at https://en.wikipedia.org/wiki/Empty_product for further 
discussion.

- Bergi

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#31272

For your reference, records indicate that 
Andreas Bergmaier <andber93@web.de> wrote:

> There's no need for debate. `true` and `false` are the identity values 
> for the AND and OR operations.

Which has absolutely *no* bearing on what these functions should 
return *to the caller*.  I don’t give a damn whether or not they use 
identities internally just like Math does for max/min.  What I care 
about is if they *output* a result that doesn’t make sense across 
their range of input.

> > At a higher level, it doesn’t make
> > sense to say that something is true for *every* object in a
> > collection, but it is *not* true for some of them.
> 
> Well, you won't find any object in the empty collection for which it is 
> not true.

And I bet you’re the kind of guy that also thinks he’s being clever 
when asked “Soup or salad?” in a restaurant and you reply “Yes!”

> May I refer you to https://en.wikipedia.org/wiki/Vacuous_truth?

The operative word to focus on there is not “truth” but “vacuous”.  
I strive to write programs that are more than vacuous.  Care to 
join me?

> >> And would you object to [].sum() being 0 and [].product being 1?  (I
> >> know ECMAScript has neither, I'm just interested in how you see similar
> >> situations.)
> >
> > A sum does essentially start at zero, so I have no objection to that.
> > I don’t know any mathematical concept of a product that can similarly
> > be said to have a set value.
> 
> Not knowing about something doesn't imply it would not exist :-) The 
> identity element of multiplication is 1.

Again, this has nothing to do with mathematical identities and 
everything to do with competent computer science and engineering 
complex systems.  *No* regular person sees a product/multiplication 
as an operation on anything less than 2 numbers.  Saying “But I 
know how to get an answer all the way down to 0 numbers!” doesn’t 
make you a good developer, it makes you some who shouldn’t be 
working in a field outside of pure math.

The better CS argument is not that product() should be 1, but that 
we shouldn’t even allow sum() to default to 0.  But even as a CS 
argument that can be a tough sell, because we coerce so *very* many 
zero-like values to 0 already.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31268

On Tue, 6 Sep 2016 16:48:36 -0000 (UTC), Doc O'Leary
<droleary@2015usenet1.subsume.com> wrote:

[snip]

>A sum does essentially start at zero, so I have no objection to that.  
>I don’t know any mathematical concept of a product that can similarly 
>be said to have a set value.

     A product "starts" at one.

     Examples are 0th powers and 0! which are all 1 (except 0 to the 0
which is undefined).

[snip]

Sincerely,

Gene Wirchenko

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#31273

For your reference, records indicate that 
Gene Wirchenko <genew@telus.net> wrote:

> On Tue, 6 Sep 2016 16:48:36 -0000 (UTC), Doc O'Leary
> <droleary@2015usenet1.subsume.com> wrote:
> 
> [snip]
> 
> >A sum does essentially start at zero, so I have no objection to that.  
> >I don’t know any mathematical concept of a product that can similarly 
> >be said to have a set value.
> 
>      A product "starts" at one.

No, it doesn’t.  It certainly has 1 as its identity, but that’s not 
the same thing.  Do yourself a favor and talk to real people about 
their understanding of math before you *ever* write any software you 
expect them to use on a daily basis.

A fun thought experiment: what was the identity element for the 
addition operation before 0 was invented?  :-)

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31291

On Wed, 7 Sep 2016 20:21:31 -0000 (UTC), Doc O'Leary
<droleary@2015usenet1.subsume.com> wrote:

>For your reference, records indicate that 
>Gene Wirchenko <genew@telus.net> wrote:
>
>> On Tue, 6 Sep 2016 16:48:36 -0000 (UTC), Doc O'Leary
>> <droleary@2015usenet1.subsume.com> wrote:
>> 
>> [snip]
>> 
>> >A sum does essentially start at zero, so I have no objection to that.  
>> >I don?t know any mathematical concept of a product that can similarly 
>> >be said to have a set value.
>> 
>>      A product "starts" at one.
>
>No, it doesn’t.  It certainly has 1 as its identity, but that’s not 

     Actually, it does.  When you initialise for a chain
multiplication, the initialisation value is 1.

>the same thing.  Do yourself a favor and talk to real people about 
>their understanding of math before you *ever* write any software you 
>expect them to use on a daily basis.

     Oh, I have.  I minored in math.  Number theory is a particular
interest of mine.

>A fun thought experiment: what was the identity element for the 
>addition operation before 0 was invented?  :-)

Sincerely,

Gene Wirchenko

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#31292

 Doc O'Leary wrote:
> A fun thought experiment: what was the identity element for the addition operation before 0 was invented?  :-)

Undefined. Such an understandimg and theory of Alhebraic structures came after the discovery of zero. (Galios and Group Theory)

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#31296

On Friday, September 9, 2016 at 5:36:19 PM UTC-5, Michael Haufe (TNO) wrote:
> Doc O'Leary wrote:
> > A fun thought experiment: what was the identity element for the addition operation before 0 was invented?  :-)
> 
> Undefined. Such an understandimg and theory of Alhebraic structures came after the discovery of zero. (Galios and Group Theory)

s/Alhebraic/Algebraic

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#31304

For your reference, records indicate that 
Gene Wirchenko <genew@telus.net> wrote:

> On Wed, 7 Sep 2016 20:21:31 -0000 (UTC), Doc O'Leary
> >
> >No, it doesn’t.  It certainly has 1 as its identity, but that’s not 
> 
>      Actually, it does.  When you initialise for a chain
> multiplication, the initialisation value is 1.
> 
> >the same thing.  Do yourself a favor and talk to real people about 
> >their understanding of math before you *ever* write any software you 
> >expect them to use on a daily basis.
> 
>      Oh, I have.  I minored in math.  Number theory is a particular
> interest of mine.

So who are the non-math-geeks you talk with that describe 
multiplication as something you “initialize” in a “chain”?  I 
continue to state the obvious to not only the vast majority of the 
population, but the correct behavior from a *computer science* 
perspective: anyone calling a commonly binary function with less 
than 2 values is probably doing so in error.  Nobody but 
mathematicians care how clever it is that you can still fabricate a 
“valid” result with 0 arguments.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31341

On Sat, 10 Sep 2016 15:12:20 -0000 (UTC), Doc O'Leary
<droleary@2015usenet1.subsume.com> wrote:

[snip]

>So who are the non-math-geeks you talk with that describe 
>multiplication as something you “initialize” in a “chain”?  I 
>continue to state the obvious to not only the vast majority of the 
>population, but the correct behavior from a *computer science* 
>perspective: anyone calling a commonly binary function with less 
>than 2 values is probably doing so in error.  Nobody but 
>mathematicians care how clever it is that you can still fabricate a 
>“valid” result with 0 arguments.

     Since it is mathematics, maybe you should pay attention to how
mathematicians define it.

Sincerely,

Gene Wirchenko

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#31361

For your reference, records indicate that 
Gene Wirchenko <genew@telus.net> wrote:

>      Since it is mathematics, maybe you should pay attention to how
> mathematicians define it.

If you know neither computer science nor mathematics, and are 
unwilling to seek out even common references, you probably should 
remain silent.

“As defined in set theory, the maximum and minimum of a set are the 
greatest and least elements in the set, respectively.”

<https://en.wikipedia.org/wiki/Maxima_and_minima>

An empty set contains *no* elements.  That max/min have an identity 
is *irrelevant* to what should be returned.  It is not an element 
*in* the input set, and so it should not be returned as the output 
element.

This is the last time I’m going to bother repeating what should be 
obvious.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31251

For your reference, records indicate that 
ram@zedat.fu-berlin.de (Stefan Ram) wrote:

> Doc O'Leary  <droleary@2015usenet1.subsume.com> writes:
> >For example, if you put the numbers in an array, you might be 
> >tempted to use something like reduce() to get down to the min/max 
> >value.  Try that on an empty array and you get a TypeError.
> 
>   Works here:
> 
> |> const a = [];
> |> console.log( a.reduce( (x,y)=>Math.max(x,y), -Infinity ));
> |  -Infinity
> 
> |> const a = [ -9, 12, 2 ];
> |> console.log( a.reduce( (x,y)=>Math.max(x,y), -Infinity ));
> |  12

So you not only *supply* the infinity, but also use the Math.max() 
that is known to improperly supply it as well, and you think that 
validates your position?  At this point, it’s clear you’re just 
trolling.

-- 
"Also . . . I can kill you with my brain."
River Tam, Trash, Firefly

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#31239

On Sunday, September 4, 2016 at 7:07:06 PM UTC-4, Ben Bacarisse wrote:
> ram@zedat.fu-berlin.de (Stefan Ram) writes:
> 
> > Doc O'Leary  <droleary@2015usenet1.subsume.com> writes:
> >>They'll have to do worse if they expect to function correctly based 
> >>on the current behavior.  You could perhaps raise it as an exception 
> >>if you prefer, but it's just plain *wrong* to return a number that 
> >>wasn't given to you.
> >
> > |> 5 ** 0
> > |< 1
> >
> >   Why does it evaluate to 1?
> >
> >   5³ = 5 · 5 · 5 = 125
> >
> >   5² = 5 · 5     =  25
> >
> >   5¹ = 5         =   5
> >
> >   5° =           =   1, why??
> 
> Lots of reasons... you want 5**x to be continuous (for real x)... you
> want 5**a x 5**b = 5 ** (a+b)... and so on.

Good one. Also, 5**a / 5**a = 1 = 5**(a-a) = 5**0.

So an aside to the OP: note that we are talking about maths, not Javascript.

Over on c.l.lisp a troll asked for an apples and oranges justification.

I pointed out that two oranges in two dimensions is four oranges arrange in a square. In three dimensions we have a second layer of four oranges or eight.
In one dimension we have a line of two oranges.
In zero dimensions we have one pointillist orange.

hth, kt

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#31255

Stefan Ram wrote:

>   If I would be a teacher in an elementary school,

Let us hope that you never will.  You are insufficiently talented for 
teaching.

>   I would explain it as follows: "x ** n" means
>   "1 multiplied n times with x", this is /correct/

No, it is not.  You mean something else.

>   and gives the correct value in /all/ cases.

If your wording is corrected.  However, this is where natural language is 
starting to fail to describe precisely, and it is simpler and better to give 
the mathematical definition, x⁰ := 1, instead.

[Please do not use the degree symbol and other replacements for the correct 
characters; if you are arguing in favor of correctness, you should use 
*correct* symbols *and* punctuation, including those from the rich character 
set provided by Unicode, if necessary – ⁰, ∑, and ∏ –, and in Germanic 
languages like English a sentence-ending mark, for example, is *never* 
preceded by whitespace.  (Also, indentation should be the exception, not the 
default.)]

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.

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