include/ceed/ceed.h

/// Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other CEED contributors.
/// All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
///
/// SPDX-License-Identifier: BSD-2-Clause
///
/// This file is part of CEED:  http://github.com/ceed

/// @file
/// Public header for user and utility components of libCEED
#ifndef _ceed_h
#define _ceed_h

/// @defgroup Ceed Ceed: core components
/// @defgroup CeedVector CeedVector: storing and manipulating vectors
/// @defgroup CeedElemRestriction CeedElemRestriction: restriction from local vectors to elements
/// @defgroup CeedBasis CeedBasis: fully discrete finite element-like objects
/// @defgroup CeedQFunction CeedQFunction: independent operations at quadrature points
/// @defgroup CeedOperator CeedOperator: composed FE-type operations on vectors
///
/// @page FunctionCategories libCEED: Types of Functions libCEED provides three different header files depending upon the type of functions a user
/// requires.
/// @section Utility Utility Functions
///    These functions are intended general utilities that may be useful to libCEED developers and users.
///    These functions can generally be found in "ceed.h".
/// @section User User Functions
///    These functions are intended to be used by general users of libCEED and can generally be found in "ceed.h".
/// @section Advanced Advanced Functions
///    These functions are intended to be used by advanced users of libCEED and can generally be found in "ceed.h".
/// @section Backend Backend Developer Functions
///    These functions are intended to be used by backend developers of libCEED and can generally be found in "ceed-backend.h".
/// @section Developer Library Developer Functions
///    These functions are intended to be used by library developers of libCEED and can generally be found in "ceed-impl.h".

#if !defined(CEED_SKIP_VISIBILITY)
#define CEED_VISIBILITY(mode) __attribute__((visibility(#mode)))
#else
#define CEED_VISIBILITY(mode)
#endif

/**
  CEED_EXTERN is used in this header to denote all publicly visible symbols.

  No other file should declare publicly visible symbols, thus it should never be used outside ceed.h.
 */
#if defined(__clang_analyzer__)
#define CEED_EXTERN extern
#elif defined(__cplusplus)
#define CEED_EXTERN extern "C" CEED_VISIBILITY(default)
#else
#define CEED_EXTERN extern CEED_VISIBILITY(default)
#endif

#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>

/// Typedefs and macros used in public interfaces and user QFunction source
#include "types.h"

/// Library context created by CeedInit()
/// @ingroup CeedUser
typedef struct Ceed_private *Ceed;
/// Non-blocking Ceed interfaces return a CeedRequest.
/// To perform an operation immediately, pass \ref CEED_REQUEST_IMMEDIATE instead.
/// @ingroup CeedUser
typedef struct CeedRequest_private *CeedRequest;
/// Handle for vectors over the field \ref CeedScalar
/// @ingroup CeedVectorUser
typedef struct CeedVector_private *CeedVector;
/// Handle for object describing restriction to elements
/// @ingroup CeedElemRestrictionUser
typedef struct CeedElemRestriction_private *CeedElemRestriction;
/// Handle for object describing discrete finite element evaluations
/// @ingroup CeedBasisUser
typedef struct CeedBasis_private *CeedBasis;
/// Handle for object describing CeedQFunction fields
/// @ingroup CeedQFunctionBackend
typedef struct CeedQFunctionField_private *CeedQFunctionField;
/// Handle for object describing functions evaluated independently at quadrature points
/// @ingroup CeedQFunctionUser
typedef struct CeedQFunction_private *CeedQFunction;
/// Handle for object describing CeedOperator fields
/// @ingroup CeedOperatorBackend
typedef struct CeedOperatorField_private *CeedOperatorField;
/// Handle for object describing context data for CeedQFunctions
/// @ingroup CeedQFunctionUser
typedef struct CeedQFunctionContext_private *CeedQFunctionContext;
/// Handle for object describing registered fields for CeedQFunctionContext
/// @ingroup CeedQFunctionUser
typedef struct CeedContextFieldLabel_private *CeedContextFieldLabel;
/// Handle for object describing FE-type operators acting on vectors
///
/// Given an element restriction \f$E\f$, basis evaluator \f$B\f$, and quadrature function\f$f\f$, a CeedOperator expresses operations of the form $$
/// E^T B^T f(B E u) $$ acting on the vector \f$u\f$.
/// @ingroup CeedOperatorUser
typedef struct CeedOperator_private *CeedOperator;

CEED_EXTERN int CeedRegistryGetList(size_t *n, char ***const resources, CeedInt **array);
CEED_EXTERN int CeedInit(const char *resource, Ceed *ceed);
CEED_EXTERN int CeedReferenceCopy(Ceed ceed, Ceed *ceed_copy);
CEED_EXTERN int CeedGetResource(Ceed ceed, const char **resource);
CEED_EXTERN int CeedIsDeterministic(Ceed ceed, bool *is_deterministic);
CEED_EXTERN int CeedAddJitSourceRoot(Ceed ceed, const char *jit_source_root);
CEED_EXTERN int CeedView(Ceed ceed, FILE *stream);
CEED_EXTERN int CeedDestroy(Ceed *ceed);

CEED_EXTERN int CeedErrorImpl(Ceed, const char *, int, const char *, int, const char *, ...);
/// Raise an error on ceed object
///
/// @param ceed Ceed library context or NULL
/// @param ecode Error code (int)
/// @param ... printf-style format string followed by arguments as needed
///
/// @ingroup Ceed
/// @sa CeedSetErrorHandler()
#if defined(__clang__)
/// Use nonstandard ternary to convince the compiler/clang-tidy that this function never returns zero.
#define CeedError(ceed, ecode, ...) (CeedErrorImpl((ceed), __FILE__, __LINE__, __func__, (ecode), __VA_ARGS__), (ecode))
#else
#define CeedError(ceed, ecode, ...) CeedErrorImpl((ceed), __FILE__, __LINE__, __func__, (ecode), __VA_ARGS__) ?: (ecode)
#endif

/// Ceed error handlers
CEED_EXTERN int CeedErrorReturn(Ceed, const char *, int, const char *, int, const char *, va_list *);
CEED_EXTERN int CeedErrorStore(Ceed, const char *, int, const char *, int, const char *, va_list *);
CEED_EXTERN int CeedErrorAbort(Ceed, const char *, int, const char *, int, const char *, va_list *);
CEED_EXTERN int CeedErrorExit(Ceed, const char *, int, const char *, int, const char *, va_list *);
typedef int (*CeedErrorHandler)(Ceed, const char *, int, const char *, int, const char *, va_list *);
CEED_EXTERN int CeedSetErrorHandler(Ceed ceed, CeedErrorHandler eh);
CEED_EXTERN int CeedGetErrorMessage(Ceed, const char **err_msg);
CEED_EXTERN int CeedResetErrorMessage(Ceed, const char **err_msg);

/// libCEED library version numbering
/// @ingroup Ceed
#define CEED_VERSION_MAJOR 0
#define CEED_VERSION_MINOR 10
#define CEED_VERSION_PATCH 1
#define CEED_VERSION_RELEASE false

/// Compile-time check that the the current library version is at least as recent as the specified version.
/// This macro is typically used in
/// @code
/// #if CEED_VERSION_GE(0, 8, 0)
///   code path that needs at least 0.8.0
/// #else
///   fallback code for older versions
/// #endif
/// @endcode
///
/// A non-release version always compares as positive infinity.
///
/// @param major   Major version
/// @param minor   Minor version
/// @param patch   Patch (subminor) version
///
/// @ingroup Ceed
/// @sa CeedGetVersion()
#define CEED_VERSION_GE(major, minor, patch) \
  (!CEED_VERSION_RELEASE ||                  \
   (CEED_VERSION_MAJOR > major ||            \
    (CEED_VERSION_MAJOR == major && (CEED_VERSION_MINOR > minor || (CEED_VERSION_MINOR == minor && CEED_VERSION_PATCH >= patch)))))

CEED_EXTERN int CeedGetVersion(int *major, int *minor, int *patch, bool *release);

CEED_EXTERN int CeedGetScalarType(CeedScalarType *scalar_type);

CEED_EXTERN const char *const *CeedErrorTypes;

/// Specify memory type
///
/// Many Ceed interfaces take or return pointers to memory.
/// This enum is used to specify where the memory being provided or requested must reside.
/// @ingroup Ceed
typedef enum {
  /// Memory resides on the host
  CEED_MEM_HOST,
  /// Memory resides on a device (corresponding to \ref Ceed resource)
  CEED_MEM_DEVICE,
} CeedMemType;
CEED_EXTERN const char *const CeedMemTypes[];

CEED_EXTERN int CeedGetPreferredMemType(Ceed ceed, CeedMemType *type);

/// Conveys ownership status of arrays passed to Ceed interfaces.
/// @ingroup Ceed
typedef enum {
  /// Implementation will copy the values and not store the passed pointer.
  CEED_COPY_VALUES,
  /// Implementation can use and modify the data provided by the user, but does not take ownership.
  CEED_USE_POINTER,
  /// Implementation takes ownership of the pointer and will free using CeedFree() when done using it.
  /// The user should not assume that the pointer remains valid after ownership has been transferred.
  /// Note that arrays allocated using C++ operator new or other allocators cannot generally be freed using CeedFree().
  /// CeedFree() is capable of freeing any memory that can be freed using free().
  CEED_OWN_POINTER,
} CeedCopyMode;
CEED_EXTERN const char *const CeedCopyModes[];

/// Denotes type of vector norm to be computed
/// @ingroup CeedVector
typedef enum {
  /// L_1 norm: sum_i |x_i|
  CEED_NORM_1,
  /// L_2 norm: sqrt(sum_i |x_i|^2)
  CEED_NORM_2,
  /// L_Infinity norm: max_i |x_i|
  CEED_NORM_MAX,
} CeedNormType;

CEED_EXTERN int CeedVectorCreate(Ceed ceed, CeedSize len, CeedVector *vec);
CEED_EXTERN int CeedVectorReferenceCopy(CeedVector vec, CeedVector *vec_copy);
CEED_EXTERN int CeedVectorSetArray(CeedVector vec, CeedMemType mem_type, CeedCopyMode copy_mode, CeedScalar *array);
CEED_EXTERN int CeedVectorSetValue(CeedVector vec, CeedScalar value);
CEED_EXTERN int CeedVectorSyncArray(CeedVector vec, CeedMemType mem_type);
CEED_EXTERN int CeedVectorTakeArray(CeedVector vec, CeedMemType mem_type, CeedScalar **array);
CEED_EXTERN int CeedVectorGetArray(CeedVector vec, CeedMemType mem_type, CeedScalar **array);
CEED_EXTERN int CeedVectorGetArrayRead(CeedVector vec, CeedMemType mem_type, const CeedScalar **array);
CEED_EXTERN int CeedVectorGetArrayWrite(CeedVector vec, CeedMemType mem_type, CeedScalar **array);
CEED_EXTERN int CeedVectorRestoreArray(CeedVector vec, CeedScalar **array);
CEED_EXTERN int CeedVectorRestoreArrayRead(CeedVector vec, const CeedScalar **array);
CEED_EXTERN int CeedVectorNorm(CeedVector vec, CeedNormType type, CeedScalar *norm);
CEED_EXTERN int CeedVectorScale(CeedVector x, CeedScalar alpha);
CEED_EXTERN int CeedVectorAXPY(CeedVector y, CeedScalar alpha, CeedVector x);
CEED_EXTERN int CeedVectorPointwiseMult(CeedVector w, CeedVector x, CeedVector y);
CEED_EXTERN int CeedVectorReciprocal(CeedVector vec);
CEED_EXTERN int CeedVectorView(CeedVector vec, const char *fp_fmt, FILE *stream);
CEED_EXTERN int CeedVectorGetCeed(CeedVector vec, Ceed *ceed);
CEED_EXTERN int CeedVectorGetLength(CeedVector vec, CeedSize *length);
CEED_EXTERN int CeedVectorDestroy(CeedVector *vec);

CEED_EXTERN CeedRequest *const CEED_REQUEST_IMMEDIATE;
CEED_EXTERN CeedRequest *const CEED_REQUEST_ORDERED;
CEED_EXTERN int                CeedRequestWait(CeedRequest *req);

/// Argument for CeedOperatorSetField that vector is collocated with quadrature points, only used with CeedEvalMode CEED_EVAL_NONE
/// @ingroup CeedBasis
CEED_EXTERN const CeedBasis CEED_BASIS_COLLOCATED;

/// Argument for CeedOperatorSetField to use active input or output
/// @ingroup CeedVector
CEED_EXTERN const CeedVector CEED_VECTOR_ACTIVE;

/// Argument for CeedOperatorSetField to use no vector, used with QFunction input with eval mode CEED_EVAL_WEIGHT
/// @ingroup CeedVector
CEED_EXTERN const CeedVector CEED_VECTOR_NONE;

/// Argument for CeedOperatorSetField to use no ElemRestriction, only used with eval mode CEED_EVAL_WEIGHT.
/// @ingroup CeedElemRestriction
CEED_EXTERN const CeedElemRestriction CEED_ELEMRESTRICTION_NONE;

/// Argument for CeedOperatorCreate that QFunction is not created by user.
/// Only used for QFunctions dqf and dqfT.
/// If implemented, a backend may attempt to provide the action of these QFunctions.
/// @ingroup CeedQFunction
CEED_EXTERN const CeedQFunction CEED_QFUNCTION_NONE;

/// Denotes whether a linear transformation or its transpose should be applied
/// @ingroup CeedBasis
typedef enum {
  /// Apply the linear transformation
  CEED_NOTRANSPOSE,
  /// Apply the transpose
  CEED_TRANSPOSE
} CeedTransposeMode;
CEED_EXTERN const char *const CeedTransposeModes[];

/// Argument for CeedElemRestrictionCreateStrided that L-vector is in the Ceed backend's preferred layout.
/// This argument should only be used with vectors created by a Ceed backend.
/// @ingroup CeedElemRestriction
CEED_EXTERN const CeedInt CEED_STRIDES_BACKEND[3];

CEED_EXTERN int CeedElemRestrictionCreate(Ceed ceed, CeedInt num_elem, CeedInt elem_size, CeedInt num_comp, CeedInt comp_stride, CeedSize l_size,
                                          CeedMemType mem_type, CeedCopyMode copy_mode, const CeedInt *offsets, CeedElemRestriction *rstr);
CEED_EXTERN int CeedElemRestrictionCreateOriented(Ceed ceed, CeedInt num_elem, CeedInt elem_size, CeedInt num_comp, CeedInt comp_stride,
                                                  CeedSize l_size, CeedMemType mem_type, CeedCopyMode copy_mode, const CeedInt *offsets,
                                                  const bool *orient, CeedElemRestriction *rstr);
CEED_EXTERN int CeedElemRestrictionCreateStrided(Ceed ceed, CeedInt num_elem, CeedInt elem_size, CeedInt num_comp, CeedSize l_size,
                                                 const CeedInt strides[3], CeedElemRestriction *rstr);
CEED_EXTERN int CeedElemRestrictionCreateBlocked(Ceed ceed, CeedInt num_elem, CeedInt elem_size, CeedInt blk_size, CeedInt num_comp,
                                                 CeedInt comp_stride, CeedSize l_size, CeedMemType mem_type, CeedCopyMode copy_mode,
                                                 const CeedInt *offsets, CeedElemRestriction *rstr);
CEED_EXTERN int CeedElemRestrictionCreateBlockedStrided(Ceed ceed, CeedInt num_elem, CeedInt elem_size, CeedInt blk_size, CeedInt num_comp,
                                                        CeedSize l_size, const CeedInt strides[3], CeedElemRestriction *rstr);
CEED_EXTERN int CeedElemRestrictionReferenceCopy(CeedElemRestriction rstr, CeedElemRestriction *rstr_copy);
CEED_EXTERN int CeedElemRestrictionCreateVector(CeedElemRestriction rstr, CeedVector *lvec, CeedVector *evec);
CEED_EXTERN int CeedElemRestrictionApply(CeedElemRestriction rstr, CeedTransposeMode t_mode, CeedVector u, CeedVector ru, CeedRequest *request);
CEED_EXTERN int CeedElemRestrictionApplyBlock(CeedElemRestriction rstr, CeedInt block, CeedTransposeMode t_mode, CeedVector u, CeedVector ru,
                                              CeedRequest *request);
CEED_EXTERN int CeedElemRestrictionGetCeed(CeedElemRestriction rstr, Ceed *ceed);
CEED_EXTERN int CeedElemRestrictionGetCompStride(CeedElemRestriction rstr, CeedInt *comp_stride);
CEED_EXTERN int CeedElemRestrictionGetNumElements(CeedElemRestriction rstr, CeedInt *num_elem);
CEED_EXTERN int CeedElemRestrictionGetElementSize(CeedElemRestriction rstr, CeedInt *elem_size);
CEED_EXTERN int CeedElemRestrictionGetLVectorSize(CeedElemRestriction rstr, CeedSize *l_size);
CEED_EXTERN int CeedElemRestrictionGetNumComponents(CeedElemRestriction rstr, CeedInt *num_comp);
CEED_EXTERN int CeedElemRestrictionGetNumBlocks(CeedElemRestriction rstr, CeedInt *num_blk);
CEED_EXTERN int CeedElemRestrictionGetBlockSize(CeedElemRestriction rstr, CeedInt *blk_size);
CEED_EXTERN int CeedElemRestrictionGetMultiplicity(CeedElemRestriction rstr, CeedVector mult);
CEED_EXTERN int CeedElemRestrictionView(CeedElemRestriction rstr, FILE *stream);
CEED_EXTERN int CeedElemRestrictionDestroy(CeedElemRestriction *rstr);

// The formalism here is that we have the structure
//  \int_\Omega v^T f_0(u, \nabla u, qdata) + (\nabla v)^T f_1(u, \nabla u, qdata)
// where gradients are with respect to the reference element.

/// Basis evaluation mode
///
/// Modes can be bitwise ORed when passing to most functions.
/// @ingroup CeedBasis
typedef enum {
  /// Perform no evaluation (either because there is no data or it is already at quadrature points)
  CEED_EVAL_NONE = 0,
  /// Interpolate from nodes to quadrature points
  CEED_EVAL_INTERP = 1,
  /// Evaluate gradients at quadrature points from input in a nodal basis
  CEED_EVAL_GRAD = 2,
  /// Evaluate divergence at quadrature points from input in a nodal basis
  CEED_EVAL_DIV = 4,
  /// Evaluate curl at quadrature points from input in a nodal basis
  CEED_EVAL_CURL = 8,
  /// Using no input, evaluate quadrature weights on the reference element
  CEED_EVAL_WEIGHT = 16,
} CeedEvalMode;
CEED_EXTERN const char *const CeedEvalModes[];

/// Type of quadrature; also used for location of nodes
/// @ingroup CeedBasis
typedef enum {
  /// Gauss-Legendre quadrature
  CEED_GAUSS = 0,
  /// Gauss-Legendre-Lobatto quadrature
  CEED_GAUSS_LOBATTO = 1,
} CeedQuadMode;
CEED_EXTERN const char *const CeedQuadModes[];

/// Type of basis shape to create non-tensor H1 element basis
///
/// Dimension can be extracted with bitwise AND (CeedElemTopology & 2**(dim + 2)) == TRUE
/// @ingroup CeedBasis
typedef enum {
  /// Line
  CEED_TOPOLOGY_LINE = 1 << 16 | 0,
  /// Triangle - 2D shape
  CEED_TOPOLOGY_TRIANGLE = 2 << 16 | 1,
  /// Quadralateral - 2D shape
  CEED_TOPOLOGY_QUAD = 2 << 16 | 2,
  /// Tetrahedron - 3D shape
  CEED_TOPOLOGY_TET = 3 << 16 | 3,
  /// Pyramid - 3D shape
  CEED_TOPOLOGY_PYRAMID = 3 << 16 | 4,
  /// Prism - 3D shape
  CEED_TOPOLOGY_PRISM = 3 << 16 | 5,
  /// Hexehedron - 3D shape
  CEED_TOPOLOGY_HEX = 3 << 16 | 6,
} CeedElemTopology;
CEED_EXTERN const char *const CeedElemTopologies[];

CEED_EXTERN int CeedBasisCreateTensorH1Lagrange(Ceed ceed, CeedInt dim, CeedInt num_comp, CeedInt P, CeedInt Q, CeedQuadMode quad_mode,
                                                CeedBasis *basis);
CEED_EXTERN int CeedBasisCreateTensorH1(Ceed ceed, CeedInt dim, CeedInt num_comp, CeedInt P_1d, CeedInt Q_1d, const CeedScalar *interp_1d,
                                        const CeedScalar *grad_1d, const CeedScalar *q_ref_1d, const CeedScalar *q_weight_1d, CeedBasis *basis);
CEED_EXTERN int CeedBasisCreateH1(Ceed ceed, CeedElemTopology topo, CeedInt num_comp, CeedInt num_nodes, CeedInt nqpts, const CeedScalar *interp,
                                  const CeedScalar *grad, const CeedScalar *q_ref, const CeedScalar *q_weights, CeedBasis *basis);
CEED_EXTERN int CeedBasisCreateHdiv(Ceed ceed, CeedElemTopology topo, CeedInt num_comp, CeedInt num_nodes, CeedInt nqpts, const CeedScalar *interp,
                                    const CeedScalar *div, const CeedScalar *q_ref, const CeedScalar *q_weights, CeedBasis *basis);
CEED_EXTERN int CeedBasisCreateProjection(CeedBasis basis_from, CeedBasis basis_to, CeedBasis *basis_project);
CEED_EXTERN int CeedBasisReferenceCopy(CeedBasis basis, CeedBasis *basis_copy);
CEED_EXTERN int CeedBasisView(CeedBasis basis, FILE *stream);
CEED_EXTERN int CeedBasisApply(CeedBasis basis, CeedInt num_elem, CeedTransposeMode t_mode, CeedEvalMode eval_mode, CeedVector u, CeedVector v);
CEED_EXTERN int CeedBasisGetCeed(CeedBasis basis, Ceed *ceed);
CEED_EXTERN int CeedBasisGetDimension(CeedBasis basis, CeedInt *dim);
CEED_EXTERN int CeedBasisGetTopology(CeedBasis basis, CeedElemTopology *topo);
CEED_EXTERN int CeedBasisGetNumQuadratureComponents(CeedBasis basis, CeedInt *Q_comp);
CEED_EXTERN int CeedBasisGetNumComponents(CeedBasis basis, CeedInt *num_comp);
CEED_EXTERN int CeedBasisGetNumNodes(CeedBasis basis, CeedInt *P);
CEED_EXTERN int CeedBasisGetNumNodes1D(CeedBasis basis, CeedInt *P_1d);
CEED_EXTERN int CeedBasisGetNumQuadraturePoints(CeedBasis basis, CeedInt *Q);
CEED_EXTERN int CeedBasisGetNumQuadraturePoints1D(CeedBasis basis, CeedInt *Q_1d);
CEED_EXTERN int CeedBasisGetQRef(CeedBasis basis, const CeedScalar **q_ref);
CEED_EXTERN int CeedBasisGetQWeights(CeedBasis basis, const CeedScalar **q_weights);
CEED_EXTERN int CeedBasisGetInterp(CeedBasis basis, const CeedScalar **interp);
CEED_EXTERN int CeedBasisGetInterp1D(CeedBasis basis, const CeedScalar **interp_1d);
CEED_EXTERN int CeedBasisGetGrad(CeedBasis basis, const CeedScalar **grad);
CEED_EXTERN int CeedBasisGetGrad1D(CeedBasis basis, const CeedScalar **grad_1d);
CEED_EXTERN int CeedBasisGetDiv(CeedBasis basis, const CeedScalar **div);
CEED_EXTERN int CeedBasisDestroy(CeedBasis *basis);

CEED_EXTERN int CeedGaussQuadrature(CeedInt Q, CeedScalar *q_ref_1d, CeedScalar *q_weight_1d);
CEED_EXTERN int CeedLobattoQuadrature(CeedInt Q, CeedScalar *q_ref_1d, CeedScalar *q_weight_1d);
CEED_EXTERN int CeedQRFactorization(Ceed ceed, CeedScalar *mat, CeedScalar *tau, CeedInt m, CeedInt n);
CEED_EXTERN int CeedSymmetricSchurDecomposition(Ceed ceed, CeedScalar *mat, CeedScalar *lambda, CeedInt n);
CEED_EXTERN int CeedSimultaneousDiagonalization(Ceed ceed, CeedScalar *mat_A, CeedScalar *mat_B, CeedScalar *x, CeedScalar *lambda, CeedInt n);

/** Handle for the user provided CeedQFunction callback function

 @param[in,out] ctx  User-defined context set using CeedQFunctionSetContext() or NULL
 @param[in] Q        Number of quadrature points at which to evaluate
 @param[in] in       Array of pointers to each input argument in the order provided by the user in CeedQFunctionAddInput().
                       Each array has shape `[dim, num_comp, Q]` where `dim` is the geometric dimension for \ref CEED_EVAL_GRAD (`dim=1` for \ref
CEED_EVAL_INTERP) and `num_comp` is the number of field components (`num_comp=1` for scalar fields). This results in indexing the `i`th input at
quadrature point `j` as `in[i][(d*num_comp + c)*Q + j]`.
 @param[out]   out   Array of pointers to each output array in the order provided using CeedQFunctionAddOutput().
                       The shapes are as above for \a in.

 @return An error code: 0 - success, otherwise - failure

 @ingroup CeedQFunction
**/
typedef int (*CeedQFunctionUser)(void *ctx, const CeedInt Q, const CeedScalar *const *in, CeedScalar *const *out);

CEED_EXTERN int CeedQFunctionCreateInterior(Ceed ceed, CeedInt vec_length, CeedQFunctionUser f, const char *source, CeedQFunction *qf);
CEED_EXTERN int CeedQFunctionCreateInteriorByName(Ceed ceed, const char *name, CeedQFunction *qf);
CEED_EXTERN int CeedQFunctionCreateIdentity(Ceed ceed, CeedInt size, CeedEvalMode in_mode, CeedEvalMode out_mode, CeedQFunction *qf);
CEED_EXTERN int CeedQFunctionReferenceCopy(CeedQFunction qf, CeedQFunction *qf_copy);
CEED_EXTERN int CeedQFunctionAddInput(CeedQFunction qf, const char *field_name, CeedInt size, CeedEvalMode eval_mode);
CEED_EXTERN int CeedQFunctionAddOutput(CeedQFunction qf, const char *field_name, CeedInt size, CeedEvalMode eval_mode);
CEED_EXTERN int CeedQFunctionGetFields(CeedQFunction qf, CeedInt *num_input_fields, CeedQFunctionField **input_fields, CeedInt *num_output_fields,
                                       CeedQFunctionField **output_fields);
CEED_EXTERN int CeedQFunctionSetContext(CeedQFunction qf, CeedQFunctionContext ctx);
CEED_EXTERN int CeedQFunctionSetContextWritable(CeedQFunction qf, bool is_writable);
CEED_EXTERN int CeedQFunctionSetUserFlopsEstimate(CeedQFunction qf, CeedSize flops);
CEED_EXTERN int CeedQFunctionView(CeedQFunction qf, FILE *stream);
CEED_EXTERN int CeedQFunctionGetCeed(CeedQFunction qf, Ceed *ceed);
CEED_EXTERN int CeedQFunctionApply(CeedQFunction qf, CeedInt Q, CeedVector *u, CeedVector *v);
CEED_EXTERN int CeedQFunctionDestroy(CeedQFunction *qf);

CEED_EXTERN int CeedQFunctionFieldGetName(CeedQFunctionField qf_field, char **field_name);
CEED_EXTERN int CeedQFunctionFieldGetSize(CeedQFunctionField qf_field, CeedInt *size);
CEED_EXTERN int CeedQFunctionFieldGetEvalMode(CeedQFunctionField qf_field, CeedEvalMode *eval_mode);

/// Denotes type of data stored in a CeedQFunctionContext field
/// @ingroup CeedQFunction
typedef enum {
  /// Double precision value
  CEED_CONTEXT_FIELD_DOUBLE = 1,
  /// 32 bit integer value
  CEED_CONTEXT_FIELD_INT32 = 2,
} CeedContextFieldType;
CEED_EXTERN const char *const CeedContextFieldTypes[];

/** Handle for the user provided CeedQFunctionContextDataDestroy callback function

 @param[in,out] data  User-CeedQFunctionContext data

 @return An error code: 0 - success, otherwise - failure

 @ingroup CeedQFunction
**/
typedef int (*CeedQFunctionContextDataDestroyUser)(void *data);

CEED_EXTERN int CeedQFunctionContextCreate(Ceed ceed, CeedQFunctionContext *ctx);
CEED_EXTERN int CeedQFunctionContextReferenceCopy(CeedQFunctionContext ctx, CeedQFunctionContext *ctx_copy);
CEED_EXTERN int CeedQFunctionContextSetData(CeedQFunctionContext ctx, CeedMemType mem_type, CeedCopyMode copy_mode, size_t size, void *data);
CEED_EXTERN int CeedQFunctionContextTakeData(CeedQFunctionContext ctx, CeedMemType mem_type, void *data);
CEED_EXTERN int CeedQFunctionContextGetData(CeedQFunctionContext ctx, CeedMemType mem_type, void *data);
CEED_EXTERN int CeedQFunctionContextGetDataRead(CeedQFunctionContext ctx, CeedMemType mem_type, void *data);
CEED_EXTERN int CeedQFunctionContextRestoreData(CeedQFunctionContext ctx, void *data);
CEED_EXTERN int CeedQFunctionContextRestoreDataRead(CeedQFunctionContext ctx, void *data);
CEED_EXTERN int CeedQFunctionContextRegisterDouble(CeedQFunctionContext ctx, const char *field_name, size_t field_offset, size_t num_values,
                                                   const char *field_description);
CEED_EXTERN int CeedQFunctionContextRegisterInt32(CeedQFunctionContext ctx, const char *field_name, size_t field_offset, size_t num_values,
                                                  const char *field_description);
CEED_EXTERN int CeedQFunctionContextGetAllFieldLabels(CeedQFunctionContext ctx, const CeedContextFieldLabel **field_labels, CeedInt *num_fields);
CEED_EXTERN int CeedContextFieldLabelGetDescription(CeedContextFieldLabel label, const char **field_name, const char **field_description,
                                                    size_t *num_values, CeedContextFieldType *field_type);
CEED_EXTERN int CeedQFunctionContextGetContextSize(CeedQFunctionContext ctx, size_t *ctx_size);
CEED_EXTERN int CeedQFunctionContextView(CeedQFunctionContext ctx, FILE *stream);
CEED_EXTERN int CeedQFunctionContextSetDataDestroy(CeedQFunctionContext ctx, CeedMemType f_mem_type, CeedQFunctionContextDataDestroyUser f);
CEED_EXTERN int CeedQFunctionContextDestroy(CeedQFunctionContext *ctx);

CEED_EXTERN int CeedOperatorCreate(Ceed ceed, CeedQFunction qf, CeedQFunction dqf, CeedQFunction dqfT, CeedOperator *op);
CEED_EXTERN int CeedCompositeOperatorCreate(Ceed ceed, CeedOperator *op);
CEED_EXTERN int CeedOperatorReferenceCopy(CeedOperator op, CeedOperator *op_copy);
CEED_EXTERN int CeedOperatorSetField(CeedOperator op, const char *field_name, CeedElemRestriction r, CeedBasis b, CeedVector v);
CEED_EXTERN int CeedOperatorGetFields(CeedOperator op, CeedInt *num_input_fields, CeedOperatorField **input_fields, CeedInt *num_output_fields,
                                      CeedOperatorField **output_fields);
CEED_EXTERN int CeedCompositeOperatorAddSub(CeedOperator composite_op, CeedOperator sub_op);
CEED_EXTERN int CeedCompositeOperatorGetNumSub(CeedOperator op, CeedInt *num_suboperators);
CEED_EXTERN int CeedCompositeOperatorGetSubList(CeedOperator op, CeedOperator **sub_operators);
CEED_EXTERN int CeedOperatorCheckReady(CeedOperator op);
CEED_EXTERN int CeedOperatorGetActiveVectorLengths(CeedOperator op, CeedSize *input_size, CeedSize *output_size);
CEED_EXTERN int CeedOperatorSetQFunctionAssemblyReuse(CeedOperator op, bool reuse_assembly_data);
CEED_EXTERN int CeedOperatorSetQFunctionAssemblyDataUpdateNeeded(CeedOperator op, bool needs_data_update);
CEED_EXTERN int CeedOperatorLinearAssembleQFunction(CeedOperator op, CeedVector *assembled, CeedElemRestriction *rstr, CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssembleQFunctionBuildOrUpdate(CeedOperator op, CeedVector *assembled, CeedElemRestriction *rstr,
                                                                 CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssembleDiagonal(CeedOperator op, CeedVector assembled, CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssembleAddDiagonal(CeedOperator op, CeedVector assembled, CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssemblePointBlockDiagonal(CeedOperator op, CeedVector assembled, CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssembleAddPointBlockDiagonal(CeedOperator op, CeedVector assembled, CeedRequest *request);
CEED_EXTERN int CeedOperatorLinearAssembleSymbolic(CeedOperator op, CeedSize *num_entries, CeedInt **rows, CeedInt **cols);
CEED_EXTERN int CeedOperatorLinearAssemble(CeedOperator op, CeedVector values);
CEED_EXTERN int CeedCompositeOperatorGetMultiplicity(CeedOperator op, CeedInt num_skip_indices, CeedInt *skip_indices, CeedVector mult);
CEED_EXTERN int CeedOperatorMultigridLevelCreate(CeedOperator op_fine, CeedVector p_mult_fine, CeedElemRestriction rstr_coarse,
                                                 CeedBasis basis_coarse, CeedOperator *op_coarse, CeedOperator *op_prolong,
                                                 CeedOperator *op_restrict);
CEED_EXTERN int CeedOperatorMultigridLevelCreateTensorH1(CeedOperator op_fine, CeedVector p_mult_fine, CeedElemRestriction rstr_coarse,
                                                         CeedBasis basis_coarse, const CeedScalar *interp_c_to_f, CeedOperator *op_coarse,
                                                         CeedOperator *op_prolong, CeedOperator *op_restrict);
CEED_EXTERN int CeedOperatorMultigridLevelCreateH1(CeedOperator op_fine, CeedVector p_mult_fine, CeedElemRestriction rstr_coarse,
                                                   CeedBasis basis_coarse, const CeedScalar *interp_c_to_f, CeedOperator *op_coarse,
                                                   CeedOperator *op_prolong, CeedOperator *op_restrict);
CEED_EXTERN int CeedOperatorCreateFDMElementInverse(CeedOperator op, CeedOperator *fdm_inv, CeedRequest *request);
CEED_EXTERN int CeedOperatorSetNumQuadraturePoints(CeedOperator op, CeedInt num_qpts);
CEED_EXTERN int CeedOperatorSetName(CeedOperator op, const char *name);
CEED_EXTERN int CeedOperatorView(CeedOperator op, FILE *stream);
CEED_EXTERN int CeedOperatorGetCeed(CeedOperator op, Ceed *ceed);
CEED_EXTERN int CeedOperatorGetNumElements(CeedOperator op, CeedInt *num_elem);
CEED_EXTERN int CeedOperatorGetNumQuadraturePoints(CeedOperator op, CeedInt *num_qpts);
CEED_EXTERN int CeedOperatorGetFlopsEstimate(CeedOperator op, CeedSize *flops);
CEED_EXTERN int CeedOperatorContextGetFieldLabel(CeedOperator op, const char *field_name, CeedContextFieldLabel *field_label);
CEED_EXTERN int CeedOperatorContextSetDouble(CeedOperator op, CeedContextFieldLabel field_label, double *values);
CEED_EXTERN int CeedOperatorContextSetInt32(CeedOperator op, CeedContextFieldLabel field_label, int *values);
CEED_EXTERN int CeedOperatorApply(CeedOperator op, CeedVector in, CeedVector out, CeedRequest *request);
CEED_EXTERN int CeedOperatorApplyAdd(CeedOperator op, CeedVector in, CeedVector out, CeedRequest *request);
CEED_EXTERN int CeedOperatorDestroy(CeedOperator *op);

CEED_EXTERN int CeedOperatorFieldGetName(CeedOperatorField op_field, char **field_name);
CEED_EXTERN int CeedOperatorFieldGetElemRestriction(CeedOperatorField op_field, CeedElemRestriction *rstr);
CEED_EXTERN int CeedOperatorFieldGetBasis(CeedOperatorField op_field, CeedBasis *basis);
CEED_EXTERN int CeedOperatorFieldGetVector(CeedOperatorField op_field, CeedVector *vec);

/**
  @brief Return integer power

  @param[in] base  The base to exponentiate
  @param[in] power The power to raise the base to

  @return base^power

  @ref Utility
**/
static inline CeedInt CeedIntPow(CeedInt base, CeedInt power) {
  CeedInt result = 1;
  while (power) {
    if (power & 1) result *= base;
    power >>= 1;
    base *= base;
  }
  return result;
}

/**
  @brief Return minimum of two integers

  @param[in] a The first integer to compare
  @param[in] b The second integer to compare

  @return The minimum of the two integers

  @ref Utility
**/
static inline CeedInt CeedIntMin(CeedInt a, CeedInt b) { return a < b ? a : b; }

/**
  @brief Return maximum of two integers

  @param[in] a The first integer to compare
  @param[in] b The second integer to compare

  @return The maximum of the two integers

  @ref Utility
**/
static inline CeedInt CeedIntMax(CeedInt a, CeedInt b) { return a > b ? a : b; }

// Used to ensure initialization before CeedInit()
CEED_EXTERN int CeedRegisterAll(void);
// Used to ensure initialization before CeedQFunctionCreate*()
CEED_EXTERN int CeedQFunctionRegisterAll(void);

#endif