precision

问题 With reg to this question Pi in C# I coded the below code and gives a output with last 6 digits as 0. So I want to improve the program by converting everything to decimal. I have never used decimal in C# instead of a double before and I am only comfortable with double in my regular use. So please help me with decimal conversion, i tried to replace all double to decimal at start and it didnt turn good :(. using System; class Program { static void Main() { Console.WriteLine(" Get PI from

问题 I'm doing some works on NLTK with named entity recognition and chunkers. I retrained a classifier using nltk/chunk/named_entity.py for that and I got the following mesures: ChunkParse score: IOB Accuracy: 96.5% Precision: 78.0% Recall: 91.9% F-Measure: 84.4% But I don't understand what is the exact difference between IOB Accuracy and Precision in this case. Actually, I found on the docs (here) the following for an specific example: The IOB tag accuracy indicates that more than a third of the

问题 I have to add trailing zeros to a decimal value. Not only for displaying (so Format is not an option), but in the actual underlying data, because the decimal precision is important in our application. I tried: decimal value = 1M decimal withPrecision = value + 0.000M; Which works well in many cases ... strangely not in all. I debugged into a case where the value in withPrecision was still 1M, by not seeing any difference in the value at runtime and the same hardcoded value in the immediate

问题 i've set up an attribute in my entity like this : /** * @var decimal * * @ORM\Column(name="latitude", type="decimal", precision=10, scale=7, nullable=true) */ private $latitude; but when i generate the database schema with : doctrine:database:create; doctrine:schema:create my field is set up to decimal (10,0) in the database (when i look up with phpmyadmin) and so, when in insert data like 42.123456 with a form, this data is truncated to 42 . how can i resolve this? Thanks. 回答1: Ok, finally

问题 I am a bit confused about how rounding in Python works. Could someone please explain why Python behaves like this? Example: >>> round(0.05,1) # this makes sense 0.1 >>> round(0.15,1) # this doesn't make sense! Why is the result not 0.2? 0.1 And same for: >>> round(0.25,1) # this makes sense 0.3 >>> round(0.35,1) # in my opinion, should be 0.4 but evaluates to 0.3 0.3 Edit: So in general, there is a possibility that Python rounds down instead of rounding up. So am I to understand that the only

问题 Are floating point operations in Delphi deterministic? I.E. will I get the same result from an identical floating point mathematical operation on the same executable compiled with Delphi Win32 compiler as I would with the Win64 compiler, or the OS X compiler, or the iOS compiler, or the Android compiler? This is a crucial question as I'm implementing multiplayer support in my game engine, and I'm concerned that the predictive results on the client side could very often differ from the

问题 The first line below will print 0.8999999999999999 because of precision loss, this is clear. But the second line will print 0.9 , I just do not understand why. Shouldn't there be the same problem with this calculation? System.out.println(2.00-1.10); System.out.printf("%f",2.00-1.10); 回答1: I think you are missing something as using System.out.printf(), if you do not explicit formatting widths then default behavior of printf in C (which is 6 decimal places if not explicitly specified) So if you

问题 I'm learning Ruby for fun, and for creating websites also (but that's irrelevant). While playing with it, i noticed something "weird" When I compute 4.21 + 5 with irb, it answers 9.21 (weird, right?) when I compute 4.23 + 5, it gives 9.23 (waw, that's definitely weird). and when i type 4.22 + 5, it answers 9.21999... (w...wait! that's really weird). Hence my question: what's going on? I'd understand this behavior with division or really big numbers, but in this simple case....??? Does it mean

问题 Using Microsoft Excel 2010. Why do these two formulae produce different results? = (0.5 - 0.4 - 0.1) produces -2.775E-17 while = 0.5 - 0.4 - 0.1 produces exactly 0. The only difference is in the brackets. Does Excel try to do clever things with floating-point numbers that it thinks should be a certain value instead of another value in order to hide the usual problems of binary floating-point and make it look as though it's using decimal arithmetic? Is this documented? 来源： https:/

问题 I wonder if there is something like eps to represent the value of machine precision in C++? Can I use it as the smallest positive number that a double can represent? Is it possible to use 1.0/eps as the max positive number that a double can represent? Where can I find eps in both C++ and C standard libraries? Thanks and regards! UPDATE: For my purpose, I would like to compute a weight as reciprocal of a distance for something like inverse distance weighting interpolation (http://en.wikipedia