I hate floating point operations
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WTF are you talking about? Please read about floating addition and multiplication. http://en.wikipedia.org/wiki/Floating_point#Floating_point_arithmetic_operations[^] Even though both suffer from rounding problems, multiplication doesn't suffer from "cancellation or absorption problems". I have run into many instances where addition based algorithms had huge precision problems that were eliminated by recoding the software to be more multiplication based.
Tim Smith I'm going to patent thought. I have yet to see any prior art.
Tim Smith wrote:
WTF are you talking about?
It was about rounding precision, but it doesn't matter, I don't seem able to make myslf understood in that thread :sigh:
Tim Smith wrote:
http://en.wikipedia.org/wiki/Floating\_point#Floating\_point\_arithmetic\_operations\[^\]
Thanks for the link.
Where do you expect us to go when the bombs fall?
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Yeah - floating point numbers should be called "approximate" to remind us not to use them when we want exact figures.
'--8<------------------------ Ex Datis: Duncan Jones Merrion Computing Ltd
Ah, yes, "approximate" and "doubly approximate". Then maybe David St. Hubbins' girlfriend's statement "you should do it in doubly" might make some sense.
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There used to be a warning message that stated 'equality comparisions between floating point values may not be meaningful.' or something like that. of course that was a long time ago on a Fortran compiler...;) Didn't this come up a month or so ago???
rollei35guy wrote:
that was a long time ago on a Fortran compiler
It can be put in the 'positive points about fortran' column... That makes two, with the efficient math libraries (matrix were well handled IIRC) :)
Where do you expect us to go when the bombs fall?
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Floating point values stump the brightest. A week or two ago, I had an argument with an quite bright student, I only barely won :cool:
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We are a big screwed up dysfunctional psychotic happy family - some more screwed up, others more happy, but everybody's psychotic joint venture definition of CP
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rollei35guy wrote:
that was a long time ago on a Fortran compiler
It can be put in the 'positive points about fortran' column... That makes two, with the efficient math libraries (matrix were well handled IIRC) :)
Where do you expect us to go when the bombs fall?
K(arl) wrote:
It can be put in the 'positive points about fortran' column... That makes two, with the efficient math libraries (matrix were well handled IIRC)
:laugh:
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When I was writing a tax calculation app many years ago, I wrote a function called AlmostEqual that looked something like this: bool AlmostEqual(double nVal1, double nVal2, int nPrecision) { CString sVal1; CString sVal2; nPrecision = _min(16, nPrecision); sVal1.Format("%.*lf", nPrecision, nVal1); sVal2.Format("%.*lf", nPrecision, nVal2); return (sVal1 == sVal2); } We had a need to check for equality at different precisions depending on where in the calculation cycle we were. I'm sure you can come up with many other ways to do the same thing, but this was fast and worked very well.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001 -
Where did you hide the body? :-D
Where do you expect us to go when the bombs fall?
He was last seen "alive" in the hardware R&D department. :cool:
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We are a big screwed up dysfunctional psychotic happy family - some more screwed up, others more happy, but everybody's psychotic joint venture definition of CP
Linkify!|Fold With Us! -
That's one way of putting it. :omg:
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K(arl) wrote:
I hate floating point operations
So do we. Any data type where "equality of values" is ill-defined is clearly half-baked. Someone should have put a more thought and less transistors into the matter.
The concept of numerical equality is a human concept that you are trying to enforce on a world where it doesn't exist. Two lengths are never exactly equal. Any collection of particles will always have virtual particles which are constantly being created and destroyed. If you say I have two baseballs or 5 nails, none of those objects are the same, you are only counting the number of objects that fit the abstract concept of baseball or nail. Exact equality only works with these abstract concepts. If you take that approach, floating point values are a good representation of lengths because lengths get the same errors when you add and multiply them using physical tools like a straightedge and compass. Integers and scaled are a better fit for abstract concepts like money which isn't a real thing.
Using the GridView is like trying to explain to someone else how to move a third person's hands in order to tie your shoelaces for you. -Chris Maunder
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There are an awful lot of irrational numbers out there. I think I would rather have my planes and bridges built using a floating point approximation of PI rather than 355/113 >In either case, the concept of "equal values" can be defined and implemented with rigor, consistency, and reliability. It's a pity these concepts don't actually appear in real life. You postulate that the universe isn't continous but is discrete, implying you believ in quantum theory, yet the basis of quantum theory itself is that there is an inherent uncertainty in all measurements. >Secondly, as popular as the metric system may be in many countries, we find it much less effective in everyday life than the English system. That's because you live in a country that uses the Imperial system. I buy food that is weighed in grams, and buy petrol and milk in litres, and need to know how many kilometres there are till my turnoff. If I ever talk in halves or quarters I mean it in a vague way ("half a loaf of bread, please") and there is no need for accuracy.
cheers, Chris Maunder
CodeProject.com : C++ MVP
Also don't forget - There is a wave nature to light. The universe may be considered discreet for SOME applications, but there is a duality to matter. Every object has a wavelength... I suppose we don't need calculus anymore - what use are derivatives anyway? We'll just cut everything into super tiny rectangles, since a wave can't have a continuous curve...What was Newton thinking?