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Ken Hutson <ken### [at] goettingcom> wrote:
> This is incorrect.
> abs(A) Absolute value of A. If A is negative, returns -A otherwise returns
> A.
How is it incorrect?
--
- Warp
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Warp <war### [at] tagpovrayorg> wrote:
> Ken Hutson <ken### [at] goettingcom> wrote:
> > This is incorrect.
>
> > abs(A) Absolute value of A. If A is negative, returns -A otherwise returns
> > A.
>
> How is it incorrect?
>
> --
> - Warp
abs(A) will ALWAYS return a positive value (or zero, of course.). AFAIK,
that's what "absolute" means.
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Kenneth wrote:
> Warp <war### [at] tagpovrayorg> wrote:
>> Ken Hutson <ken### [at] goettingcom> wrote:
>>> This is incorrect.
>>> abs(A) Absolute value of A. If A is negative, returns -A otherwise returns
>>> A.
>> How is it incorrect?
>>
>> --
>> - Warp
>
> abs(A) will ALWAYS return a positive value (or zero, of course.). AFAIK,
> that's what "absolute" means.
>
>
Quick quiz: What is the negative of a negative number. (Hint: its not a
double negative...)
--
~Mike
Things! Billions of them!
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Perhaps the word "incorrect" was a poor choice of words. I'm used to seeing
a simpler definition:
For any real number a, the absolute value of a, is denoted | a | , and is
defined as:
"Mike Raiford" <mra### [at] hotmailcom> wrote in message
news:4343f9c5$1@news.povray.org...
> Kenneth wrote:
>> Warp <war### [at] tagpovrayorg> wrote:
>>> Ken Hutson <ken### [at] goettingcom> wrote:
>>>> This is incorrect.
>>>> abs(A) Absolute value of A. If A is negative, returns -A otherwise
>>>> returns
>>>> A.
>>> How is it incorrect?
>>>
>>> --
>>> - Warp
>>
>> abs(A) will ALWAYS return a positive value (or zero, of course.). AFAIK,
>> that's what "absolute" means.
>>
>>
>
> Quick quiz: What is the negative of a negative number. (Hint: its not a
> double negative...)
>
> --
> ~Mike
>
> Things! Billions of them!
Post a reply to this message
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Ken Hutson <ken### [at] goettingcom> wrote:
> Perhaps the word "incorrect" was a poor choice of words. I'm used to seeing
> a simpler definition:
> For any real number a, the absolute value of a, is denoted | a | , and is
> defined as:
Could you please use proper formatting of a news reply? What I see here
is a bit ridiculous.
First is your answer, which ends with "is defined as:". Immediately after
that is the whole original article quoted (beats me how that is the
definition of absolute value). After that comes a gif attachment (which,
by the way, shows only as a black square here).
I know that some braindead newsreader programs, when hitting the reply
button, will quote the entire original article, put some empty lines
*before* it and then put the cursor at the beginning, and this will tempt
you to just write your answer there. However, for the sake of clarity that's
a bad idea.
Quote only *relevant* parts of the original post. Keeping the entire
original post is just a waste of bandwidth.
Answer *after* the quote. If you are answering to several things in
the original post, put each individual answer after each individual
quote. It should look like this:
Some Name wrote:
> Some text.
My answer to this.
> More text.
Another answer.
> Yet more text.
Yet another answer.
If the original post is long and you are answering to it as a whole,
not particularly to any specific part of it, then you can leave the quote
out completely. People will be able to read the original post you are
answering to if they want. You don't need to repeat it.
--
- Warp
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"Ken Hutson" <ken### [at] goettingcom> wrote:
> Perhaps the word "incorrect" was a poor choice of words. I'm used to seeing
> a simpler definition:
>
> For any real number a, the absolute value of a, is denoted | a | , and is
> defined as:
> |a| = square root of (a squared)
Maybe they don't provide the definition for people who are already "used to
seeing it"... :)
JYR
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Mike Raiford <mra### [at] hotmailcom> wrote:
> Quick quiz: What is the negative of a negative number. (Hint: its not a
> double negative...)
Let me clarify my earlier post, with a nod to Mike Raiford's clue. I can
see now why there's a bit of confusion. POV's description is correct,
though "worded" in mathematical terms.
Say that A = 32.
abs(A) will then produce A, which is 32.
Now, say A = -32.
abs(A) will then, according to the POV doc, produce -A. Which is - (-32).
Which is again 32.
Voila!
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Kenneth <kdw### [at] earthlinknet> wrote:
> Let me clarify my earlier post, with a nod to Mike Raiford's clue. I can
> see now why there's a bit of confusion. POV's description is correct,
> though "worded" in mathematical terms.
Perhaps my mind is too spoiled by mathematics, but I really can't
understand how the definition can be confusing, given that you think
about it even for a second.
After all, it says "if A is negative the result is -A". What does anyone
expect the result to be, reading and understanding this definition?
I mean, how else could you say that so that it doesn't sound stupid?
--
- Warp
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Warp <war### [at] tagpovrayorg> wrote:
> Perhaps my mind is too spoiled by mathematics....
> - Warp
: )
It confused ME as well, when I first came across it. Don't know why...
something about "A being -A". Of course you're right. But it just "looks"
odd at first glance (well, to a non-mathematician...)
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"Kenneth" <kdw### [at] earthlinknet> wrote:
> It confused ME as well, when I first came across it. Don't know why...
> something about "A being -A". Of course you're right. But it just "looks"
> odd at first glance (well, to a non-mathematician...)
Actually, let me rephrase my reply in more general terms, as this is a topic
I've given a fair amount of thought to...
IMHO, far too many parts of the POV docs read like sections from a dry
MATHEMATICS TEXTBOOK. (Ugh!!!) I think this has a psychological "numbing"
effect on new users. (I count myself in that group!) It has been a *LONG*
time since I attended high-school and university, and it has taken me
awhile to resurrect the required math knowledge in order to make real use
of POV. Though I'm glad I did, I don't believe this needs to be so; because
with a few well-turned phrases of non-mathematical English (or whatever
language you choose), POV's pure math-like descriptions of its functions
could be made far easier to understand, especially for the beginner.
I personally think that the POV SDL is one of the brightest lights in the
CGI universe...so MANY things can be done with it (especially with its
unofficial patched versions like MEGA-POV.) But the preponderance of
"unadorned math" in the POV docs can certainly be offputting. I'll bet that
there are lots of potential POV "converts" out there who have decided that
learning to use POV is just not worth the effort. And that's unfortunate,
because they'll never realize what they're missing!
Ken
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