arpacktools.hpp

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/*
 * BELFEM -- The Berkeley Lab Finite Element Framework
 * Copyright (c) 2026, The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy).  All rights reserved.
 *
 * Developers: Christian Messe, Gregory Giard
 *
 * See the top-level LICENSE file for the complete license and disclaimer.
 */
 
#ifndef ARPACKTOOLS_HPP
#define ARPACKTOOLS_HPP
 
#include "typedefs.hpp"
 
namespace belfem
{
    namespace arpack
    {
        constexpr index_t gNumInfoEntries = 7 ;

        constexpr index_t gInfoNaupd = 0 ;

        constexpr index_t gInfoNeupd = 1 ;

        constexpr index_t gInfoNumConverged = 2 ;

        constexpr index_t gInfoNumIterations = 3 ;

        constexpr index_t gInfoNumOperations = 4 ;

        constexpr index_t gInfoNumReorthogonalizations = 5 ;

        constexpr index_t gInfoSubspaceSize = 6 ;
 
#ifdef __cplusplus
        extern"C" {
#endif

            void
            arpack_standard_eigen(
                const int_t * n,
                const int_t * nnz,
                const real * values,
                const int_t * indices,
                const int_t * pointers,
                const int_t * job,
                const int_t * nev,
                const int_t * ncvmin,
                const real  * tol,
                const int_t * maxit,
                const real  * sigma,    // 0 for OP = A, else OP = sigma*I - A
                real * lambdareal,
                real * lambdaimag,
                int_t * info ) ;

            void
            arpack_symmetric_eigen(
                const int_t * n,
                const int_t * nnz,
                const real * values,
                const int_t * indices,
                const int_t * pointers,
                const int_t * job,
                const int_t * nev,
                const int_t * ncvmin,
                const real  * tol,
                const int_t * maxit,
                const real  * sigma,    // 0 for OP = A, else OP = sigma*I - A
                real * lambdareal,
                real * lambdaimag,
                int_t * info ) ;

            void
            arpack_si_step(
                int_t * ido,
                const int_t * n,
                const int_t * nev,
                const int_t * ncv,
                real  * tol,           // dsaupd may overwrite it
                real  * resid,         // [ n ]
                real  * vectors,       // [ ldv * ncv ]
                const int_t * ldv,
                int_t * iparam,        // [ 11 ]
                int_t * ipntr,         // [ 11 ]
                real  * workd,         // [ 3 * n ]
                real  * workl,         // [ lworkl ]
                const int_t * lworkl,
                int_t * info ) ;

            void
            arpack_si_extract(
                const real  * sigma,
                const int_t * n,
                const int_t * nev,
                const int_t * ncv,
                real  * tol,
                real  * resid,
                real  * vectors,
                const int_t * ldv,
                int_t * iparam,
                int_t * ipntr,
                real  * workd,
                real  * workl,
                const int_t * lworkl,
                real  * lambdareal,    // [ nev ], eigenvalues of A
                int_t * info ) ;
 
#ifdef __cplusplus
        }
#endif

        void
        check_naupd( const int_t aInfo );

        void
        check_neupd( const int_t aInfo );

        void
        check_saupd( const int_t aInfo );

        void
        check_seupd( const int_t aInfo );
 
    }
 
}
#endif //ARPACKTOOLS_HPP