UTL HelperFunctions

UTL Module

This module contains some helper functions, logging macros, debug macros, and an N-dimensional array class implemented using expression template with support for MKL, OpenBlas, Lapack and OpenMP.

Although OOP is good, sometimes functional style of programming is more attractive, and classes are too heavy for some specific tasks, e.g. reading text lines from a file, converting a container object to another container object. Thus we prefer using some small functions for those tasks.


UTL module has only header files and can be used separately based on the different dependencies. See file dependency.

To build codes using utl::NDArray, you need to have MKL or OpenBlas + Lapack, and your compile needs to support C++11.

  • MKL is free for students, educators, academic researchers and open source contributors. See the free download link. OpenBlas and Lapack are always free and easy to use.

  • If you choose OpenBlas + Lapack, you can use them from system repositories. In this case, you need to set environment variables correctly. See FAQ of OpenBlas.

    git clone https://github.com/xianyi/OpenBLAS.git
    cd OpenBlas
    git checkout v0.2.13
    make BINARY=64 USE_THREAD=0 USE_OPENMP=1 cc=gcc  FC=gfortran
    make install


  • utl::NDArray<T,N> is an N-dimensional array based on expression template.
  • utl::NDArray<T,1> and utl::NDArray<T,2> are more efficient than vnl_vector<T> and vnl_matrix<T> because
  • You can run utlVNLBlasGTest and utlVNLLapackGTest to compare efficiency of utl::NDArray and vnl_vector, vnl_matrix.

File structure and dependency

Files Dependency Description
utlSmartAssert.h std macros for smart assert, modified based on the SMART_ASSERT library by John Torjo.
utlCoreMacro.h std macros for print and debug
utlCore.h std useful functions for general purpose
utlCore11.h std, c++11 specific useful functions for general purpose
utlCoreMKL.h std, (mkl optional) useful functions for mkl. If mkl is not found, a manual implementation is used.
utlCommandLineParser.h std small but powerful command line parser, borrowed from CImg
utlMath.h std math related functions
utlRotationMatrixFromVectors.h std functions to find rotation 3x3 matrix from two 3D vectors
utlSTDHeaders.h std macros to avoid include confliction issues for different versions of std
utlTypeinfo.h std, c++11 specific type alias for c++11
utlGTest.h google gtest useful macros for gtest
utl_cblas.h cblas header file from cblas.h. Add some macro conditions to avoid multiple definition issues from other versions of cblas.
utlBlas.h cblas, (mkl optional) templated version of interface for cblas
utlLapack.h lapack templated version of interface for lapacke
utlMKL.h mkl templated version of interface for mkl
utlExpression.h std Implementation of Expression Template to avoid temporary copies in expression.
utlFunctors.h std Some functor classes, and functions for utl::NDArray<T,N>.
utlNDArray.h std, blas, lapack, (mkl optional) utl::NDArray<T,N> class (N-dimensional array) based on expression template, blas and mkl.
utlVector.h std, blas, lapack, (mkl optional) utl::NDArray<T,1> class (vector).
utlMatrix.h std, blas, lapack, (mkl optional) utl::NDArray<T,2> class (matrix).
utl4thOrderTensor.h std, blas, lapack, (mkl optional) utl::NDArray<T,4> class (4th order tensor).
utlNDArrayFunctions.h std, blas, lapack, (mkl optional) utl::NDArray<T,N> related functions.
utlDMRI.h std, utl::NDArray Useful functions for dMRI
utlDMRIStoredTables.h std, utl::NDArray Precomputed tables for dmritool
utlOpenMP.h openmp openmp related functions
utlVNL.h vnl vnl related functions
utlVNLBlas.h vnl, blas useful functions for vnl vector and matrix using blas implementation
utlVNLLapack.h vnl, blas, lapack useful functions for vnl vector and matrix using blas and lapack implementation
utlVNLIO.h std, vnl, blas, lapack, (mkl optional) conversion between utl::NDArray and vnl_vector, vnl_matrix
utlITKMacro.h itk macros for itk
utlITK.h itk functions for itk
utlVTKMacro.h vtk macros for vtk
utl.h std, itk, blas, lapack, gsl, (mkl optional) useful functions for dmritool