1/*
2 Copyright (c) 2011, Intel Corporation. All rights reserved.
3 Copyright (C) 2011 Gael Guennebaud <gael.guennebaud@inria.fr>
4
5 Redistribution and use in source and binary forms, with or without modification,
6 are permitted provided that the following conditions are met:
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27
28 ********************************************************************************
29 *   Content : Documentation on the use of Intel MKL through Eigen
30 ********************************************************************************
31*/
32
33namespace Eigen {
34
35/** \page TopicUsingIntelMKL Using Intel® Math Kernel Library from Eigen
36
37\section TopicUsingIntelMKL_Intro Eigen and Intel® Math Kernel Library (Intel® MKL)
38
39Since Eigen version 3.1 and later, users can benefit from built-in Intel MKL optimizations with an installed copy of Intel MKL 10.3 (or later).
40<a href="http://eigen.tuxfamily.org/Counter/redirect_to_mkl.php"> Intel MKL </a> provides highly optimized multi-threaded mathematical routines for x86-compatible architectures.
41Intel MKL is available on Linux, Mac and Windows for both Intel64 and IA32 architectures.
42
43\warning Be aware that Intel® MKL is a proprietary software. It is the responsibility of the users to buy MKL licenses for their products. Moreover, the license of the user product has to allow linking to proprietary software that excludes any unmodified versions of the GPL.
44
45Using Intel MKL through Eigen is easy:
46-# define the \c EIGEN_USE_MKL_ALL macro before including any Eigen's header
47-# link your program to MKL libraries (see the <a href="http://software.intel.com/en-us/articles/intel-mkl-link-line-advisor/">MKL linking advisor</a>)
48-# on a 64bits system, you must use the LP64 interface (not the ILP64 one)
49
50When doing so, a number of Eigen's algorithms are silently substituted with calls to Intel MKL routines.
51These substitutions apply only for \b Dynamic \b or \b large enough objects with one of the following four standard scalar types: \c float, \c double, \c complex<float>, and \c complex<double>.
52Operations on other scalar types or mixing reals and complexes will continue to use the built-in algorithms.
53
54In addition you can coarsely select choose which parts will be substituted by defining one or multiple of the following macros:
55
56<table class="manual">
57<tr><td>\c EIGEN_USE_BLAS </td><td>Enables the use of external BLAS level 2 and 3 routines (currently works with Intel MKL only)</td></tr>
58<tr class="alt"><td>\c EIGEN_USE_LAPACKE </td><td>Enables the use of external Lapack routines via the <a href="http://www.netlib.org/lapack/lapacke.html">Intel Lapacke</a> C interface to Lapack (currently works with Intel MKL only)</td></tr>
59<tr><td>\c EIGEN_USE_LAPACKE_STRICT </td><td>Same as \c EIGEN_USE_LAPACKE but algorithm of lower robustness are disabled. This currently concerns only JacobiSVD which otherwise would be replaced by \c gesvd that is less robust than Jacobi rotations.</td></tr>
60<tr class="alt"><td>\c EIGEN_USE_MKL_VML </td><td>Enables the use of Intel VML (vector operations)</td></tr>
61<tr><td>\c EIGEN_USE_MKL_ALL </td><td>Defines \c EIGEN_USE_BLAS, \c EIGEN_USE_LAPACKE, and \c EIGEN_USE_MKL_VML </td></tr>
62</table>
63
64Finally, the PARDISO sparse solver shipped with Intel MKL can be used through the \ref PardisoLU, \ref PardisoLLT and \ref PardisoLDLT classes of the \ref PardisoSupport_Module.
65
66
67\section TopicUsingIntelMKL_SupportedFeatures List of supported features
68
69The breadth of Eigen functionality covered by Intel MKL is listed in the table below.
70<table class="manual">
71<tr><th>Functional domain</th><th>Code example</th><th>MKL routines</th></tr>
72<tr><td>Matrix-matrix operations \n \c EIGEN_USE_BLAS </td><td>\code
73m1*m2.transpose();
74m1.selfadjointView<Lower>()*m2;
75m1*m2.triangularView<Upper>();
76m1.selfadjointView<Lower>().rankUpdate(m2,1.0);
77\endcode</td><td>\code
78?gemm
79?symm/?hemm
80?trmm
81dsyrk/ssyrk
82\endcode</td></tr>
83<tr class="alt"><td>Matrix-vector operations \n \c EIGEN_USE_BLAS </td><td>\code
84m1.adjoint()*b;
85m1.selfadjointView<Lower>()*b;
86m1.triangularView<Upper>()*b;
87\endcode</td><td>\code
88?gemv
89?symv/?hemv
90?trmv
91\endcode</td></tr>
92<tr><td>LU decomposition \n \c EIGEN_USE_LAPACKE \n \c EIGEN_USE_LAPACKE_STRICT </td><td>\code
93v1 = m1.lu().solve(v2);
94\endcode</td><td>\code
95?getrf
96\endcode</td></tr>
97<tr class="alt"><td>Cholesky decomposition \n \c EIGEN_USE_LAPACKE \n \c EIGEN_USE_LAPACKE_STRICT </td><td>\code
98v1 = m2.selfadjointView<Upper>().llt().solve(v2);
99\endcode</td><td>\code
100?potrf
101\endcode</td></tr>
102<tr><td>QR decomposition \n \c EIGEN_USE_LAPACKE \n \c EIGEN_USE_LAPACKE_STRICT </td><td>\code
103m1.householderQr();
104m1.colPivHouseholderQr();
105\endcode</td><td>\code
106?geqrf
107?geqp3
108\endcode</td></tr>
109<tr class="alt"><td>Singular value decomposition \n \c EIGEN_USE_LAPACKE </td><td>\code
110JacobiSVD<MatrixXd> svd;
111svd.compute(m1, ComputeThinV);
112\endcode</td><td>\code
113?gesvd
114\endcode</td></tr>
115<tr><td>Eigen-value decompositions \n \c EIGEN_USE_LAPACKE \n \c EIGEN_USE_LAPACKE_STRICT </td><td>\code
116EigenSolver<MatrixXd> es(m1);
117ComplexEigenSolver<MatrixXcd> ces(m1);
118SelfAdjointEigenSolver<MatrixXd> saes(m1+m1.transpose());
119GeneralizedSelfAdjointEigenSolver<MatrixXd>
120    gsaes(m1+m1.transpose(),m2+m2.transpose());
121\endcode</td><td>\code
122?gees
123?gees
124?syev/?heev
125?syev/?heev,
126?potrf
127\endcode</td></tr>
128<tr class="alt"><td>Schur decomposition \n \c EIGEN_USE_LAPACKE \n \c EIGEN_USE_LAPACKE_STRICT </td><td>\code
129RealSchur<MatrixXd> schurR(m1);
130ComplexSchur<MatrixXcd> schurC(m1);
131\endcode</td><td>\code
132?gees
133\endcode</td></tr>
134<tr><td>Vector Math \n \c EIGEN_USE_MKL_VML </td><td>\code
135v2=v1.array().sin();
136v2=v1.array().asin();
137v2=v1.array().cos();
138v2=v1.array().acos();
139v2=v1.array().tan();
140v2=v1.array().exp();
141v2=v1.array().log();
142v2=v1.array().sqrt();
143v2=v1.array().square();
144v2=v1.array().pow(1.5);
145\endcode</td><td>\code
146v?Sin
147v?Asin
148v?Cos
149v?Acos
150v?Tan
151v?Exp
152v?Ln
153v?Sqrt
154v?Sqr
155v?Powx
156\endcode</td></tr>
157</table>
158In the examples, m1 and m2 are dense matrices and v1 and v2 are dense vectors.
159
160
161\section TopicUsingIntelMKL_Links Links
162- Intel MKL can be purchased and downloaded <a href="http://eigen.tuxfamily.org/Counter/redirect_to_mkl.php">here</a>.
163- Intel MKL is also bundled with <a href="http://software.intel.com/en-us/articles/intel-composer-xe/">Intel Composer XE</a>.
164
165
166*/
167
168}
169