#1 Trigonometric functions failure

[Philippe]

Hello,

I compiled the source (Commit 393210) using Visual Studio 2010 and I get some strange behavior with Sin and Cos functions for some specific kind of values.
It seems that the range reduction algorithm is failing but I may be wrong since I didn't read all the source code at that time.

Here are some examples of the problem:

Expression	Returns	Where it should be
Quadruple.Cos(Quadruple.HalfPi)	3.141592653589793238462643383279502	0
Quadruple.Cos(Quadruple.HalfPi + Quadruple.Pi)	6.283185307179586476925286766559005	0
Quadruple.Cos(Quadruple.FromString("7.5") *  Quadruple.Pi)	25.13274122871834590770114706623603	0
Quadruple.Sin(Quadruple.Pi)	3.141592653589793238462643383279502	0
Quadruple.Sin(Quadruple.TwoPi)	6.283185307179586476925286766559005	0
Quadruple.Sin(Quadruple.FromString("6") * Quadruple.Pi)	18.84955592153875943077586029967702	0

 

Thanks Philippe

[Philippe]

The problem can be solved by replacing the expression "if (temp.IsZero()) return v;" at the line 745 of the file __float128.cpp by "if (temp.IsZero()) return QuadZero;"