Re: Setting floating point variable as infinite
On 3/23/2012 3:01 PM, Rui Maciel wrote:
[snip irate response to something for some reason apparently taken personally]
Again, you either failed to understand what I wrote or you are intentionally
trying to misrepresent what I said [..]
Failed? Maybe. Intentionally? You know what, if you're having a bad
day, why are you trying to blame me for that? Snap at somebody who
actually gives a damn.
So, to avoid any more misconceptions or any attempts to misrepresent
anything, here is a clear description of this case.
- there is a non-empty set of data.
- there is a set of operators which map each element of that set to a
floating point number.
- the objective is to evaluate which is the minimum value of the codomain of
a particular operator.
I suggested the following approach:
<pseudo-ish code>
float minimum = std::numeric_limits<float>::infinity();
for(auto element: element_list)
{
if( operator(element)< minimum)
minimum = operator(element);
}
</pseudo-ish code>
Then, I asked if it was a good idea to do this. In other words, if there
was any reason that would made it a bad idea. Until now, no reason has been
given.
Why would a solution that works be a bad idea? Since you didn't state
the complexity of your 'operator', we could presume that it's expensive.
Then the only concern is efficiency.
The pseudo code has two inefficiencies. First, it initializes 'minimum'
to some value, and immediately overrides it with the
'operator(element#0)'. Second inefficiency is that it evaluates the
'operator' for each element twice.
Simple as that.
I also asked if there was a better way to get the minimum value.
Don't evaluate twice and initialize from the first element, and skip the
first element while doing the loop.
Simple as that.
If you need algorithm advice, consider asking in 'comp.programming'.
V
--
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