Re: Why is 0.1f + 0.2f - 0.3f produces such a large error number?
MarLOne <[email protected]>
| Newsgroups | gmane.comp.gnome.mono.general |
|---|---|
| Message-ID | <[email protected]> |
Thanks for the reply. The following disclosure may not have anything to do with explaining this but it highlights some inconsistency in .Net: I know Mono is not exactly VS (well very close as Xamarin is now part of Microsoft) but the following comparison is still valid and interesting: VS2003, 2005, 2010, 2012 all returning a delta value of -7.450581E-09 Anyone with a VS2013 can help by reporting what it produces. *VS2015 (regardless Update 1 or 2) returning 0*. Also regardless on what machine and processor type (even on mac), Swift, Java, and C all returning 0 as expected. It seems from day one the C# compiler is producing this same number until it comes to VS2015. I also had a look at the IL code generated and the compiler compiles the constant expression so the IL code does not show any arithmetic expression. I guess we can blame the compiler. But I rewrite the code in such a way the compiler cannot compile away the value at compile time. Yet I am getting the same non-zero delta. I guess Microsoft and Mono can claim that is literally zero because float according to ECMA C# standard is only good to 7 digits. But that does not explain why the other compiler/languages have so much more accuracy. Does this mean one should not use C# when performing scientific calculations? The above information is interesting. If you construct a DLL or COM component using C/C++, the return value (by P/Invoke or COM call) will be zero. If you then enhance the DLL by rewriting it in a .Net component, the return value to a .net client is -7.450581E-09!! The same client but component developed with different languages. Is this a good language to deal with integration? May be that's why VS2015 took the decision to fix it. When will a mono compiler matching VS2015's? Leon -- View this message in context: http://mono.1490590.n4.nabble.com/Why-is-0-1f-0-2f-0-3f-produces-such-a-large-error-number-tp4667837p4667848.html Sent from the Mono - General mailing list archive at Nabble.com. _______________________________________________ Mono-list maillist - [email protected] http://lists.ximian.com/mailman/listinfo/mono-list