cart-elc

Source code for CART-ELC
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Constants.h (21931B)


      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2008-2015 Gael Guennebaud <gael.guennebaud@inria.fr>
      5 // Copyright (C) 2007-2009 Benoit Jacob <jacob.benoit.1@gmail.com>
      6 // Copyright (C) 2020, Arm Limited and Contributors
      7 //
      8 // This Source Code Form is subject to the terms of the Mozilla
      9 // Public License v. 2.0. If a copy of the MPL was not distributed
     10 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
     11 
     12 #ifndef EIGEN_CONSTANTS_H
     13 #define EIGEN_CONSTANTS_H
     14 
     15 namespace Eigen {
     16 
     17 /** This value means that a positive quantity (e.g., a size) is not known at compile-time, and that instead the value is
     18   * stored in some runtime variable.
     19   *
     20   * Changing the value of Dynamic breaks the ABI, as Dynamic is often used as a template parameter for Matrix.
     21   */
     22 const int Dynamic = -1;
     23 
     24 /** This value means that a signed quantity (e.g., a signed index) is not known at compile-time, and that instead its value
     25   * has to be specified at runtime.
     26   */
     27 const int DynamicIndex = 0xffffff;
     28 
     29 /** This value means that the increment to go from one value to another in a sequence is not constant for each step.
     30   */
     31 const int UndefinedIncr = 0xfffffe;
     32 
     33 /** This value means +Infinity; it is currently used only as the p parameter to MatrixBase::lpNorm<int>().
     34   * The value Infinity there means the L-infinity norm.
     35   */
     36 const int Infinity = -1;
     37 
     38 /** This value means that the cost to evaluate an expression coefficient is either very expensive or
     39   * cannot be known at compile time.
     40   *
     41   * This value has to be positive to (1) simplify cost computation, and (2) allow to distinguish between a very expensive and very very expensive expressions.
     42   * It thus must also be large enough to make sure unrolling won't happen and that sub expressions will be evaluated, but not too large to avoid overflow.
     43   */
     44 const int HugeCost = 10000;
     45 
     46 /** \defgroup flags Flags
     47   * \ingroup Core_Module
     48   *
     49   * These are the possible bits which can be OR'ed to constitute the flags of a matrix or
     50   * expression.
     51   *
     52   * It is important to note that these flags are a purely compile-time notion. They are a compile-time property of
     53   * an expression type, implemented as enum's. They are not stored in memory at runtime, and they do not incur any
     54   * runtime overhead.
     55   *
     56   * \sa MatrixBase::Flags
     57   */
     58 
     59 /** \ingroup flags
     60   *
     61   * for a matrix, this means that the storage order is row-major.
     62   * If this bit is not set, the storage order is column-major.
     63   * For an expression, this determines the storage order of
     64   * the matrix created by evaluation of that expression.
     65   * \sa \blank  \ref TopicStorageOrders */
     66 const unsigned int RowMajorBit = 0x1;
     67 
     68 /** \ingroup flags
     69   * means the expression should be evaluated by the calling expression */
     70 const unsigned int EvalBeforeNestingBit = 0x2;
     71 
     72 /** \ingroup flags
     73   * \deprecated
     74   * means the expression should be evaluated before any assignment */
     75 EIGEN_DEPRECATED
     76 const unsigned int EvalBeforeAssigningBit = 0x4; // FIXME deprecated
     77 
     78 /** \ingroup flags
     79   *
     80   * Short version: means the expression might be vectorized
     81   *
     82   * Long version: means that the coefficients can be handled by packets
     83   * and start at a memory location whose alignment meets the requirements
     84   * of the present CPU architecture for optimized packet access. In the fixed-size
     85   * case, there is the additional condition that it be possible to access all the
     86   * coefficients by packets (this implies the requirement that the size be a multiple of 16 bytes,
     87   * and that any nontrivial strides don't break the alignment). In the dynamic-size case,
     88   * there is no such condition on the total size and strides, so it might not be possible to access
     89   * all coeffs by packets.
     90   *
     91   * \note This bit can be set regardless of whether vectorization is actually enabled.
     92   *       To check for actual vectorizability, see \a ActualPacketAccessBit.
     93   */
     94 const unsigned int PacketAccessBit = 0x8;
     95 
     96 #ifdef EIGEN_VECTORIZE
     97 /** \ingroup flags
     98   *
     99   * If vectorization is enabled (EIGEN_VECTORIZE is defined) this constant
    100   * is set to the value \a PacketAccessBit.
    101   *
    102   * If vectorization is not enabled (EIGEN_VECTORIZE is not defined) this constant
    103   * is set to the value 0.
    104   */
    105 const unsigned int ActualPacketAccessBit = PacketAccessBit;
    106 #else
    107 const unsigned int ActualPacketAccessBit = 0x0;
    108 #endif
    109 
    110 /** \ingroup flags
    111   *
    112   * Short version: means the expression can be seen as 1D vector.
    113   *
    114   * Long version: means that one can access the coefficients
    115   * of this expression by coeff(int), and coeffRef(int) in the case of a lvalue expression. These
    116   * index-based access methods are guaranteed
    117   * to not have to do any runtime computation of a (row, col)-pair from the index, so that it
    118   * is guaranteed that whenever it is available, index-based access is at least as fast as
    119   * (row,col)-based access. Expressions for which that isn't possible don't have the LinearAccessBit.
    120   *
    121   * If both PacketAccessBit and LinearAccessBit are set, then the
    122   * packets of this expression can be accessed by packet(int), and writePacket(int) in the case of a
    123   * lvalue expression.
    124   *
    125   * Typically, all vector expressions have the LinearAccessBit, but there is one exception:
    126   * Product expressions don't have it, because it would be troublesome for vectorization, even when the
    127   * Product is a vector expression. Thus, vector Product expressions allow index-based coefficient access but
    128   * not index-based packet access, so they don't have the LinearAccessBit.
    129   */
    130 const unsigned int LinearAccessBit = 0x10;
    131 
    132 /** \ingroup flags
    133   *
    134   * Means the expression has a coeffRef() method, i.e. is writable as its individual coefficients are directly addressable.
    135   * This rules out read-only expressions.
    136   *
    137   * Note that DirectAccessBit and LvalueBit are mutually orthogonal, as there are examples of expression having one but note
    138   * the other:
    139   *   \li writable expressions that don't have a very simple memory layout as a strided array, have LvalueBit but not DirectAccessBit
    140   *   \li Map-to-const expressions, for example Map<const Matrix>, have DirectAccessBit but not LvalueBit
    141   *
    142   * Expressions having LvalueBit also have their coeff() method returning a const reference instead of returning a new value.
    143   */
    144 const unsigned int LvalueBit = 0x20;
    145 
    146 /** \ingroup flags
    147   *
    148   * Means that the underlying array of coefficients can be directly accessed as a plain strided array. The memory layout
    149   * of the array of coefficients must be exactly the natural one suggested by rows(), cols(),
    150   * outerStride(), innerStride(), and the RowMajorBit. This rules out expressions such as Diagonal, whose coefficients,
    151   * though referencable, do not have such a regular memory layout.
    152   *
    153   * See the comment on LvalueBit for an explanation of how LvalueBit and DirectAccessBit are mutually orthogonal.
    154   */
    155 const unsigned int DirectAccessBit = 0x40;
    156 
    157 /** \deprecated \ingroup flags
    158   *
    159   * means the first coefficient packet is guaranteed to be aligned.
    160   * An expression cannot have the AlignedBit without the PacketAccessBit flag.
    161   * In other words, this means we are allow to perform an aligned packet access to the first element regardless
    162   * of the expression kind:
    163   * \code
    164   * expression.packet<Aligned>(0);
    165   * \endcode
    166   */
    167 EIGEN_DEPRECATED const unsigned int AlignedBit = 0x80;
    168 
    169 const unsigned int NestByRefBit = 0x100;
    170 
    171 /** \ingroup flags
    172   *
    173   * for an expression, this means that the storage order
    174   * can be either row-major or column-major.
    175   * The precise choice will be decided at evaluation time or when
    176   * combined with other expressions.
    177   * \sa \blank  \ref RowMajorBit, \ref TopicStorageOrders */
    178 const unsigned int NoPreferredStorageOrderBit = 0x200;
    179 
    180 /** \ingroup flags
    181   *
    182   * Means that the underlying coefficients can be accessed through pointers to the sparse (un)compressed storage format,
    183   * that is, the expression provides:
    184   * \code
    185     inline const Scalar* valuePtr() const;
    186     inline const Index* innerIndexPtr() const;
    187     inline const Index* outerIndexPtr() const;
    188     inline const Index* innerNonZeroPtr() const;
    189     \endcode
    190   */
    191 const unsigned int CompressedAccessBit = 0x400;
    192 
    193 
    194 // list of flags that are inherited by default
    195 const unsigned int HereditaryBits = RowMajorBit
    196                                   | EvalBeforeNestingBit;
    197 
    198 /** \defgroup enums Enumerations
    199   * \ingroup Core_Module
    200   *
    201   * Various enumerations used in %Eigen. Many of these are used as template parameters.
    202   */
    203 
    204 /** \ingroup enums
    205   * Enum containing possible values for the \c Mode or \c UpLo parameter of
    206   * MatrixBase::selfadjointView() and MatrixBase::triangularView(), and selfadjoint solvers. */
    207 enum UpLoType {
    208   /** View matrix as a lower triangular matrix. */
    209   Lower=0x1,                      
    210   /** View matrix as an upper triangular matrix. */
    211   Upper=0x2,                      
    212   /** %Matrix has ones on the diagonal; to be used in combination with #Lower or #Upper. */
    213   UnitDiag=0x4, 
    214   /** %Matrix has zeros on the diagonal; to be used in combination with #Lower or #Upper. */
    215   ZeroDiag=0x8,
    216   /** View matrix as a lower triangular matrix with ones on the diagonal. */
    217   UnitLower=UnitDiag|Lower, 
    218   /** View matrix as an upper triangular matrix with ones on the diagonal. */
    219   UnitUpper=UnitDiag|Upper,
    220   /** View matrix as a lower triangular matrix with zeros on the diagonal. */
    221   StrictlyLower=ZeroDiag|Lower, 
    222   /** View matrix as an upper triangular matrix with zeros on the diagonal. */
    223   StrictlyUpper=ZeroDiag|Upper,
    224   /** Used in BandMatrix and SelfAdjointView to indicate that the matrix is self-adjoint. */
    225   SelfAdjoint=0x10,
    226   /** Used to support symmetric, non-selfadjoint, complex matrices. */
    227   Symmetric=0x20
    228 };
    229 
    230 /** \ingroup enums
    231   * Enum for indicating whether a buffer is aligned or not. */
    232 enum AlignmentType {
    233   Unaligned=0,        /**< Data pointer has no specific alignment. */
    234   Aligned8=8,         /**< Data pointer is aligned on a 8 bytes boundary. */
    235   Aligned16=16,       /**< Data pointer is aligned on a 16 bytes boundary. */
    236   Aligned32=32,       /**< Data pointer is aligned on a 32 bytes boundary. */
    237   Aligned64=64,       /**< Data pointer is aligned on a 64 bytes boundary. */
    238   Aligned128=128,     /**< Data pointer is aligned on a 128 bytes boundary. */
    239   AlignedMask=255,
    240   Aligned=16,         /**< \deprecated Synonym for Aligned16. */
    241 #if EIGEN_MAX_ALIGN_BYTES==128
    242   AlignedMax = Aligned128
    243 #elif EIGEN_MAX_ALIGN_BYTES==64
    244   AlignedMax = Aligned64
    245 #elif EIGEN_MAX_ALIGN_BYTES==32
    246   AlignedMax = Aligned32
    247 #elif EIGEN_MAX_ALIGN_BYTES==16
    248   AlignedMax = Aligned16
    249 #elif EIGEN_MAX_ALIGN_BYTES==8
    250   AlignedMax = Aligned8
    251 #elif EIGEN_MAX_ALIGN_BYTES==0
    252   AlignedMax = Unaligned
    253 #else
    254 #error Invalid value for EIGEN_MAX_ALIGN_BYTES
    255 #endif
    256 };
    257 
    258 /** \ingroup enums
    259   * Enum containing possible values for the \p Direction parameter of
    260   * Reverse, PartialReduxExpr and VectorwiseOp. */
    261 enum DirectionType { 
    262   /** For Reverse, all columns are reversed; 
    263     * for PartialReduxExpr and VectorwiseOp, act on columns. */
    264   Vertical, 
    265   /** For Reverse, all rows are reversed; 
    266     * for PartialReduxExpr and VectorwiseOp, act on rows. */
    267   Horizontal, 
    268   /** For Reverse, both rows and columns are reversed; 
    269     * not used for PartialReduxExpr and VectorwiseOp. */
    270   BothDirections 
    271 };
    272 
    273 /** \internal \ingroup enums
    274   * Enum to specify how to traverse the entries of a matrix. */
    275 enum TraversalType {
    276   /** \internal Default traversal, no vectorization, no index-based access */
    277   DefaultTraversal,
    278   /** \internal No vectorization, use index-based access to have only one for loop instead of 2 nested loops */
    279   LinearTraversal,
    280   /** \internal Equivalent to a slice vectorization for fixed-size matrices having good alignment
    281     * and good size */
    282   InnerVectorizedTraversal,
    283   /** \internal Vectorization path using a single loop plus scalar loops for the
    284     * unaligned boundaries */
    285   LinearVectorizedTraversal,
    286   /** \internal Generic vectorization path using one vectorized loop per row/column with some
    287     * scalar loops to handle the unaligned boundaries */
    288   SliceVectorizedTraversal,
    289   /** \internal Special case to properly handle incompatible scalar types or other defecting cases*/
    290   InvalidTraversal,
    291   /** \internal Evaluate all entries at once */
    292   AllAtOnceTraversal
    293 };
    294 
    295 /** \internal \ingroup enums
    296   * Enum to specify whether to unroll loops when traversing over the entries of a matrix. */
    297 enum UnrollingType {
    298   /** \internal Do not unroll loops. */
    299   NoUnrolling,
    300   /** \internal Unroll only the inner loop, but not the outer loop. */
    301   InnerUnrolling,
    302   /** \internal Unroll both the inner and the outer loop. If there is only one loop, 
    303     * because linear traversal is used, then unroll that loop. */
    304   CompleteUnrolling
    305 };
    306 
    307 /** \internal \ingroup enums
    308   * Enum to specify whether to use the default (built-in) implementation or the specialization. */
    309 enum SpecializedType {
    310   Specialized,
    311   BuiltIn
    312 };
    313 
    314 /** \ingroup enums
    315   * Enum containing possible values for the \p _Options template parameter of
    316   * Matrix, Array and BandMatrix. */
    317 enum StorageOptions {
    318   /** Storage order is column major (see \ref TopicStorageOrders). */
    319   ColMajor = 0,
    320   /** Storage order is row major (see \ref TopicStorageOrders). */
    321   RowMajor = 0x1,  // it is only a coincidence that this is equal to RowMajorBit -- don't rely on that
    322   /** Align the matrix itself if it is vectorizable fixed-size */
    323   AutoAlign = 0,
    324   /** Don't require alignment for the matrix itself (the array of coefficients, if dynamically allocated, may still be requested to be aligned) */ // FIXME --- clarify the situation
    325   DontAlign = 0x2
    326 };
    327 
    328 /** \ingroup enums
    329   * Enum for specifying whether to apply or solve on the left or right. */
    330 enum SideType {
    331   /** Apply transformation on the left. */
    332   OnTheLeft = 1,
    333   /** Apply transformation on the right. */
    334   OnTheRight = 2
    335 };
    336 
    337 /** \ingroup enums
    338  * Enum for specifying NaN-propagation behavior, e.g. for coeff-wise min/max. */
    339 enum NaNPropagationOptions {
    340   /**  Implementation defined behavior if NaNs are present. */
    341   PropagateFast = 0,
    342   /**  Always propagate NaNs. */
    343   PropagateNaN,
    344   /**  Always propagate not-NaNs. */
    345   PropagateNumbers
    346 };
    347 
    348 /* the following used to be written as:
    349  *
    350  *   struct NoChange_t {};
    351  *   namespace {
    352  *     EIGEN_UNUSED NoChange_t NoChange;
    353  *   }
    354  *
    355  * on the ground that it feels dangerous to disambiguate overloaded functions on enum/integer types.  
    356  * However, this leads to "variable declared but never referenced" warnings on Intel Composer XE,
    357  * and we do not know how to get rid of them (bug 450).
    358  */
    359 
    360 enum NoChange_t   { NoChange };
    361 enum Sequential_t { Sequential };
    362 enum Default_t    { Default };
    363 
    364 /** \internal \ingroup enums
    365   * Used in AmbiVector. */
    366 enum AmbiVectorMode {
    367   IsDense         = 0,
    368   IsSparse
    369 };
    370 
    371 /** \ingroup enums
    372   * Used as template parameter in DenseCoeffBase and MapBase to indicate 
    373   * which accessors should be provided. */
    374 enum AccessorLevels {
    375   /** Read-only access via a member function. */
    376   ReadOnlyAccessors, 
    377   /** Read/write access via member functions. */
    378   WriteAccessors, 
    379   /** Direct read-only access to the coefficients. */
    380   DirectAccessors, 
    381   /** Direct read/write access to the coefficients. */
    382   DirectWriteAccessors
    383 };
    384 
    385 /** \ingroup enums
    386   * Enum with options to give to various decompositions. */
    387 enum DecompositionOptions {
    388   /** \internal Not used (meant for LDLT?). */
    389   Pivoting            = 0x01, 
    390   /** \internal Not used (meant for LDLT?). */
    391   NoPivoting          = 0x02, 
    392   /** Used in JacobiSVD to indicate that the square matrix U is to be computed. */
    393   ComputeFullU        = 0x04,
    394   /** Used in JacobiSVD to indicate that the thin matrix U is to be computed. */
    395   ComputeThinU        = 0x08,
    396   /** Used in JacobiSVD to indicate that the square matrix V is to be computed. */
    397   ComputeFullV        = 0x10,
    398   /** Used in JacobiSVD to indicate that the thin matrix V is to be computed. */
    399   ComputeThinV        = 0x20,
    400   /** Used in SelfAdjointEigenSolver and GeneralizedSelfAdjointEigenSolver to specify
    401     * that only the eigenvalues are to be computed and not the eigenvectors. */
    402   EigenvaluesOnly     = 0x40,
    403   /** Used in SelfAdjointEigenSolver and GeneralizedSelfAdjointEigenSolver to specify
    404     * that both the eigenvalues and the eigenvectors are to be computed. */
    405   ComputeEigenvectors = 0x80,
    406   /** \internal */
    407   EigVecMask = EigenvaluesOnly | ComputeEigenvectors,
    408   /** Used in GeneralizedSelfAdjointEigenSolver to indicate that it should
    409     * solve the generalized eigenproblem \f$ Ax = \lambda B x \f$. */
    410   Ax_lBx              = 0x100,
    411   /** Used in GeneralizedSelfAdjointEigenSolver to indicate that it should
    412     * solve the generalized eigenproblem \f$ ABx = \lambda x \f$. */
    413   ABx_lx              = 0x200,
    414   /** Used in GeneralizedSelfAdjointEigenSolver to indicate that it should
    415     * solve the generalized eigenproblem \f$ BAx = \lambda x \f$. */
    416   BAx_lx              = 0x400,
    417   /** \internal */
    418   GenEigMask = Ax_lBx | ABx_lx | BAx_lx
    419 };
    420 
    421 /** \ingroup enums
    422   * Possible values for the \p QRPreconditioner template parameter of JacobiSVD. */
    423 enum QRPreconditioners {
    424   /** Do not specify what is to be done if the SVD of a non-square matrix is asked for. */
    425   NoQRPreconditioner,
    426   /** Use a QR decomposition without pivoting as the first step. */
    427   HouseholderQRPreconditioner,
    428   /** Use a QR decomposition with column pivoting as the first step. */
    429   ColPivHouseholderQRPreconditioner,
    430   /** Use a QR decomposition with full pivoting as the first step. */
    431   FullPivHouseholderQRPreconditioner
    432 };
    433 
    434 #ifdef Success
    435 #error The preprocessor symbol 'Success' is defined, possibly by the X11 header file X.h
    436 #endif
    437 
    438 /** \ingroup enums
    439   * Enum for reporting the status of a computation. */
    440 enum ComputationInfo {
    441   /** Computation was successful. */
    442   Success = 0,        
    443   /** The provided data did not satisfy the prerequisites. */
    444   NumericalIssue = 1, 
    445   /** Iterative procedure did not converge. */
    446   NoConvergence = 2,
    447   /** The inputs are invalid, or the algorithm has been improperly called.
    448     * When assertions are enabled, such errors trigger an assert. */
    449   InvalidInput = 3
    450 };
    451 
    452 /** \ingroup enums
    453   * Enum used to specify how a particular transformation is stored in a matrix.
    454   * \sa Transform, Hyperplane::transform(). */
    455 enum TransformTraits {
    456   /** Transformation is an isometry. */
    457   Isometry      = 0x1,
    458   /** Transformation is an affine transformation stored as a (Dim+1)^2 matrix whose last row is 
    459     * assumed to be [0 ... 0 1]. */
    460   Affine        = 0x2,
    461   /** Transformation is an affine transformation stored as a (Dim) x (Dim+1) matrix. */
    462   AffineCompact = 0x10 | Affine,
    463   /** Transformation is a general projective transformation stored as a (Dim+1)^2 matrix. */
    464   Projective    = 0x20
    465 };
    466 
    467 /** \internal \ingroup enums
    468   * Enum used to choose between implementation depending on the computer architecture. */
    469 namespace Architecture
    470 {
    471   enum Type {
    472     Generic = 0x0,
    473     SSE = 0x1,
    474     AltiVec = 0x2,
    475     VSX = 0x3,
    476     NEON = 0x4,
    477     MSA = 0x5,
    478     SVE = 0x6,
    479 #if defined EIGEN_VECTORIZE_SSE
    480     Target = SSE
    481 #elif defined EIGEN_VECTORIZE_ALTIVEC
    482     Target = AltiVec
    483 #elif defined EIGEN_VECTORIZE_VSX
    484     Target = VSX
    485 #elif defined EIGEN_VECTORIZE_NEON
    486     Target = NEON
    487 #elif defined EIGEN_VECTORIZE_SVE
    488     Target = SVE
    489 #elif defined EIGEN_VECTORIZE_MSA
    490     Target = MSA
    491 #else
    492     Target = Generic
    493 #endif
    494   };
    495 }
    496 
    497 /** \internal \ingroup enums
    498   * Enum used as template parameter in Product and product evaluators. */
    499 enum ProductImplType
    500 { DefaultProduct=0, LazyProduct, AliasFreeProduct, CoeffBasedProductMode, LazyCoeffBasedProductMode, OuterProduct, InnerProduct, GemvProduct, GemmProduct };
    501 
    502 /** \internal \ingroup enums
    503   * Enum used in experimental parallel implementation. */
    504 enum Action {GetAction, SetAction};
    505 
    506 /** The type used to identify a dense storage. */
    507 struct Dense {};
    508 
    509 /** The type used to identify a general sparse storage. */
    510 struct Sparse {};
    511 
    512 /** The type used to identify a general solver (factored) storage. */
    513 struct SolverStorage {};
    514 
    515 /** The type used to identify a permutation storage. */
    516 struct PermutationStorage {};
    517 
    518 /** The type used to identify a permutation storage. */
    519 struct TranspositionsStorage {};
    520 
    521 /** The type used to identify a matrix expression */
    522 struct MatrixXpr {};
    523 
    524 /** The type used to identify an array expression */
    525 struct ArrayXpr {};
    526 
    527 // An evaluator must define its shape. By default, it can be one of the following:
    528 struct DenseShape             { static std::string debugName() { return "DenseShape"; } };
    529 struct SolverShape            { static std::string debugName() { return "SolverShape"; } };
    530 struct HomogeneousShape       { static std::string debugName() { return "HomogeneousShape"; } };
    531 struct DiagonalShape          { static std::string debugName() { return "DiagonalShape"; } };
    532 struct BandShape              { static std::string debugName() { return "BandShape"; } };
    533 struct TriangularShape        { static std::string debugName() { return "TriangularShape"; } };
    534 struct SelfAdjointShape       { static std::string debugName() { return "SelfAdjointShape"; } };
    535 struct PermutationShape       { static std::string debugName() { return "PermutationShape"; } };
    536 struct TranspositionsShape    { static std::string debugName() { return "TranspositionsShape"; } };
    537 struct SparseShape            { static std::string debugName() { return "SparseShape"; } };
    538 
    539 namespace internal {
    540 
    541   // random access iterators based on coeff*() accessors.
    542 struct IndexBased {};
    543 
    544 // evaluator based on iterators to access coefficients. 
    545 struct IteratorBased {};
    546 
    547 /** \internal
    548  * Constants for comparison functors
    549  */
    550 enum ComparisonName {
    551   cmp_EQ = 0,
    552   cmp_LT = 1,
    553   cmp_LE = 2,
    554   cmp_UNORD = 3,
    555   cmp_NEQ = 4,
    556   cmp_GT = 5,
    557   cmp_GE = 6
    558 };
    559 } // end namespace internal
    560 
    561 } // end namespace Eigen
    562 
    563 #endif // EIGEN_CONSTANTS_H