76d752585b
to a little figure out what Guido had done & why -- but there is a neat saving of force evaluations across the nesting time boundary making use of linearity of the leapP in dt. I cleaned up the printing, reduced the volume of code, in the process sharing printing between all integrators. Placed an assert that the total integration time for all integrators must match at end of trajectory. Have now verified e-dH = 1 for nested integrators in Wilson/Wilson runs with both Omelyan and with Leapfrog so substantial confidence gained. |
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| configure | ||
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Grid
Data parallel C++ mathematical object library
This library provides data parallel C++ container classes with internal memory layout that is transformed to map efficiently to SIMD architectures. CSHIFT facilities are provided, similar to HPF and cmfortran, and user control is given over the mapping of array indices to both MPI tasks and SIMD processing elements.
- Identically shaped arrays then be processed with perfect data parallelisation.
- Such identically shapped arrays are called conformable arrays.
The transformation is based on the observation that Cartesian array processing involves identical processing to be performed on different regions of the Cartesian array.
The library will both geometrically decompose into MPI tasks and across SIMD lanes. Local vector loops are parallelised with OpenMP pragmas.
Data parallel array operations can then be specified with a SINGLE data parallel paradigm, but optimally use MPI, OpenMP and SIMD parallelism under the hood. This is a significant simplification for most programmers.
The layout transformations are parametrised by the SIMD vector length. This adapts according to the architecture. Presently SSE4 (128 bit) AVX, AVX2 (256 bit) and IMCI and AVX512 (512 bit) targets are supported.
These are presented as
vRealF, vRealD, vComplexF, vComplexD
internal vector data types. These may be useful in themselves for other programmers. The corresponding scalar types are named
RealF, RealD, ComplexF, ComplexD
MPI, OpenMP, and SIMD parallelism are present in the library.
You can give `configure' initial values for configuration parameters by setting variables in the command line or in the environment. Here are examples:
./configure CXX=clang++ CXXFLAGS="-std=c++11 -O3 -msse4" --enable-simd=SSE4
./configure CXX=clang++ CXXFLAGS="-std=c++11 -O3 -mavx" --enable-simd=AVX1
./configure CXX=clang++ CXXFLAGS="-std=c++11 -O3 -mavx2" --enable-simd=AVX2
./configure CXX=icpc CXXFLAGS="-std=c++11 -O3 -mmic" --enable-simd=AVX512 --host=none
For developers: Use reconfigure_script in the scripts/ directory to create the autotools environment