hasinf.hpp

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//
// Copyright (c) 2025, University of Colorado Denver. All rights reserved.
//
// This file is part of <T>LAPACK.
// <T>LAPACK is free software: you can redistribute it and/or modify it under
// the terms of the BSD 3-Clause license. See the accompanying LICENSE file.
 
#ifndef TLAPACK_HASINF_HH
#define TLAPACK_HASINF_HH
 
#include "tlapack/base/utils.hpp"
 
namespace tlapack {
 
template <TLAPACK_UPLO uplo_t, TLAPACK_MATRIX matrix_t>
bool hasinf(uplo_t uplo, const matrix_t& A)
{
    using idx_t = size_type<matrix_t>;
 
    // constants
    const idx_t m = nrows(A);
    const idx_t n = ncols(A);
 
    tlapack_check(uplo == Uplo::General || uplo == Uplo::UpperHessenberg ||
                  uplo == Uplo::LowerHessenberg || uplo == Uplo::Upper ||
                  uplo == Uplo::Lower || uplo == Uplo::StrictUpper ||
                  uplo == Uplo::StrictLower);
 
    if (uplo == Uplo::UpperHessenberg) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = 0; i < ((j < m) ? j + 2 : m); ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else if (uplo == Uplo::Upper) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = 0; i < ((j < m) ? j + 1 : m); ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else if (uplo == Uplo::StrictUpper) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = 0; i < ((j < m) ? j : m); ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else if (uplo == Uplo::LowerHessenberg) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = ((j > 1) ? j - 1 : 0); i < m; ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else if (uplo == Uplo::Lower) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = j; i < m; ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else if (uplo == Uplo::StrictLower) {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = j + 1; i < m; ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
    else  // if ( (Uplo) uplo == Uplo::General )
    {
        for (idx_t j = 0; j < n; ++j)
            for (idx_t i = 0; i < m; ++i)
                if (isinf(A(i, j))) return true;
        return false;
    }
}
 
template <TLAPACK_MATRIX matrix_t>
bool hasinf(BandAccess accessType, const matrix_t& A) noexcept
{
    using idx_t = size_type<matrix_t>;
 
    // constants
    const idx_t m = nrows(A);
    const idx_t n = ncols(A);
    const idx_t kl = accessType.lower_bandwidth;
    const idx_t ku = accessType.upper_bandwidth;
 
    for (idx_t j = 0; j < n; ++j)
        for (idx_t i = ((j >= ku) ? (j - ku) : 0); i < min(m, j + kl + 1); ++i)
            if (isinf(A(i, j))) return true;
    return false;
}
 
template <TLAPACK_VECTOR vector_t>
bool hasinf(const vector_t& x) noexcept
{
    using idx_t = size_type<vector_t>;
 
    // constants
    const idx_t n = size(x);
 
    for (idx_t i = 0; i < n; ++i)
        if (isinf(x[i])) return true;
    return false;
}
 
}  // namespace tlapack
 
#endif  // TLAPACK_HASINF_HH