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Questions tagged [quadruple-precision]

quadruple precision is a binary floating-point-based computer number format that occupies 16 bytes (128 bits).

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Quadruple Precision in C++ (GCC)

Just recently, the GCC 4.6.0 came out along with libquadmath. Unfortunately, GNU has supported Fortran, but not C or C++ (all that is included is a .so). I have not found a way to use these new features in C++, however, GNU C does support the…
RétroX
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Strange result of MPI_AllReduce for 16 byte real

Compiler: gfortran-4.8.5 MPI library: OpenMPI-1.7.2 (preinstalled OpenSuSE 13.2) This program: use mpi implicit none real*16 :: x integer :: ierr, irank, type16 call MPI_Init(ierr) call MPI_Comm_Rank(MPI_Comm_World, irank, ierr) if…
Vladimir F
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Epsilon in quadruple precision (gcc)

According to wikipedia, the layouts of the different precision data types are single precision: exponent (e): 8 bits, fraction (f): 23 bits double precision: e: 11 bits, f: 52 bits quadruple precision: e: 15 bits, f: 112 bits. I wrote a small…
okruz
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Quadruple precision in G++ 4.6.3 Linux using quadmath

I try to execute the code #include #include int main() { char* y = new char[1000]; quadmath_snprintf(y, 1000, "%Qf", 1.0q); std::cout << y << std::endl; return 0; } with commands g++ test.cpp -o test I get the…
dStack
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CPU time in quadruple vs. double precision

I am doing some long-term simulations in which I'm trying to achieve the highest possible accuracy in the solution of systems of ODEs. I am trying to find out how much time quadruple (128-bit) precision calculations take versus double (64-bit)…
LeWavite
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quadmath and argument type for scanf

I use the . With which argument type can I read my input correctly? If I use double it looks like: printf("enter 3 values for s, t and mt:\n"); scanf("%lf %lf %lf", &s, &t, &mt); printf("%lf %lf %lf\n", s, t, mt); I tried different…
maniA
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Set the default real type to an 16 byte in c program

With gfortran compiler, the flag -fdefault-real-16 helps to set the default real type to an 16 byte wide type. for example program qp_test implicit none double precision :: a a = 123456789012345678.123456789012345678 …
Mohammed CHIKH BAELHADJ
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MPICH libraries for quadruple precision not recognised by FFTW3?

I am converting my parallel double precision fortran code that involves calls to FFTW3 and BLAS-LAPACK packages to parallel quadruple precision. I have installed FFTW3 for quadruple precision as follows: ./configure --enable-quad-precision…
sai
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Quadruple precision float support on Intel C++ compiler 18.0 update 3 in vs 2017

I just tried to compile a C++ program with boost::multiprecision::float128 support in Visual Studio 2017 using Intel C++ compiler 18.0 update 3. I add /Qoption,cpp,--extended_float_type to project C/C++ additional options. However, ICC emit E0020:…
S. Nie
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Strange behaviour using quadruple precision in Fortran using Mingw (Anaconda version)

Windows 7 64 bits GNU Fortran (GCC) 4.7.0 20111220 (experimental) --> The MinGW version installed with Anaconda3/Miniconda3 64 bits. Hi all, I'm trying to compile some Fortran code to be used from Python using F2Py. The full project is Solcore,…
dalonsoa
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Quadruple precision on Linux vs. Mac

I have written a multi-dimensional numerical integration code which is able to run at double, long double or quadruple precision in Linux. All modes compile and work flawlessly but when I try to compile the same code for the quadruple precision case…
Yeti
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Why optimization flag (-O3) doesn't speed up quadruple precision calculations?

I have a high-precision ODE (ordinary differential equations) solver written on C++. I do all calculations with user-defined type real_type. There is a typedef declaring this type in the header: typedef long double real_type; I decided to change…
Alex Koksin
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Taking square root to quadruple precision

How can I do a square root for Real(Real128)?
Zeus
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Why is my C++ program so slow when switching from long double to float128?

I program on Unix, using the g++ 4.8.2 compiler. I currently need to convert my C++ program, which at this point uses long double (with a significand of 64 bits in my case), to a program which uses the __float128 type (with a significand of 113…
Thomas Prest
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long double subnormals/denormals get truncated to 0 [-Woverflow]

In the IEEE754 standarad, the minimum strictly positive (subnormal) value is 2−16493 ≈ 10−4965 using Quadruple-precision floating-point format. Why does GCC reject anything lower than 10-4949? I'm looking for an explanation of the different things…
Harvinder
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