Hello, I think the inaccuracy is connected with standard float point arithmetic. If you will use instead the command: cout<<(numeric(1, 10)+numeric(7))<<endl; cout<<(numeric(1, 100)*numeric("9"))<<endl; cout<<(numeric(1, 100)*numeric("99"))<<endl; cout<<(numeric(1, 10)+numeric(7)).evalf()<<endl; cout<<(numeric(1, 100)*numeric("9")).evalf()<<endl; cout<<(numeric(1, 100)*numeric("99")).evalf()<<endl; you will get: 71/10 9/100 99/100 7.1 0.09 0.99 Best wishes, Vladimir -- Vladimir V. Kisil http://v-v-kisil.scienceontheweb.net Book: Geometry of Mobius Maps https://doi.org/10.1142/p835 Soft: Geometry of cycles http://moebinv.sourceforge.net/ Jupyter notebooks: https://github.com/vvkisil?tab=repositories
On Sat, 26 Oct 2024 21:08:13 +0530, "Dr. Mithun Bairagi" <bairagirasulpur@gmail.com> said:
MB> Dear all ginac lovers, I have got some wrong results when MB> performing some simple computations using ginac. I have MB> compiled and run the following c++ program using ginac-1.8.7, MB> cln-1.3.7 (mingw64 compiler, gcc version 14.2.0, windows 10 os), MB> #include <ginac/ginac.h> MB> using namespace std; using namespace GiNaC; MB> int main() { cout<<(numeric(0.1)+numeric(7))<<endl; MB> cout<<(numeric("0.01")*numeric("9"))<<endl; MB> cout<<(numeric("0.01")*numeric("99"))<<endl; } MB> the above program shows the following result: MB> 7.1000000000000000056 0.089999999999999999996 MB> 0.98999999999999999995 MB> I have got some unwanted digits which look very ugly. I think MB> the result should be 7.1 0.09 0.99 MB> Best regards, Mithun Bairagi