Line data    Source code

       1            1 : // Distributed under the MIT License.
       2              : // See LICENSE.txt for details.
       3              : 
       4              : /// \file
       5              : /// Declares functions for interpolating data in volume files to target points.
       6              : /// This file is intended to be included in external programs, so it
       7              : /// intentionally has no dependencies on any other headers.
       8              : 
       9              : #pragma once
      10              : 
      11              : #include <array>
      12              : #include <cstddef>
      13              : #include <limits>
      14              : #include <optional>
      15              : #include <string>
      16              : #include <variant>
      17              : #include <vector>
      18              : 
      19              : /// Functions that are intended to be used by external programs, e.g. to
      20              : /// interpolate data in volume files to target points.
      21            0 : namespace spectre::Exporter {
      22              : 
      23              : /// Identifies an observation by its ID in the volume data file.
      24            1 : struct ObservationId {
      25            0 :   ObservationId() = default;
      26            0 :   explicit ObservationId(size_t local_value) : value(local_value) {}
      27            0 :   size_t value;
      28              : };
      29              : 
      30              : /// Identifies an observation by its index in the ordered list of observations.
      31              : /// Negative indices are counted from the end of the list.
      32            1 : struct ObservationStep {
      33            0 :   ObservationStep() = default;
      34            0 :   explicit ObservationStep(int local_value) : value(local_value) {}
      35            0 :   int value;
      36              : };
      37              : 
      38              : /// Identifies an observation by its value (e.g. the time), selecting the
      39              : /// observation whose value is closest to `value` within `epsilon`. This is the
      40              : /// same selection as a bare `double`, but with a configurable tolerance.
      41            1 : struct ObservationValue {
      42            0 :   ObservationValue() = default;
      43            0 :   explicit ObservationValue(double local_value, double local_epsilon = 1e-12)
      44              :       : value(local_value), epsilon(local_epsilon) {}
      45            0 :   double value = std::numeric_limits<double>::signaling_NaN();
      46            0 :   double epsilon = 1e-12;
      47              : };
      48              : 
      49            0 : using ObservationVariant =
      50              :     std::variant<ObservationId, ObservationStep, double, ObservationValue>;
      51              : 
      52              : /*!
      53              :  * \brief Interpolate data in volume files to target points
      54              :  *
      55              :  * \tparam Dim Dimension of the domain
      56              :  * \param volume_files_or_glob The list of H5 files, or a glob pattern
      57              :  * \param subfile_name The name of the subfile in the H5 files containing the
      58              :  * volume data
      59              :  * \param observation Either the observation ID as a `size_t`, or the index of
      60              :  * the observation in the volume files to interpolate as an `int` (a value of 0
      61              :  * would be the first observation, and a value of -1 would be the last
      62              :  * observation).
      63              :  * \param tensor_components The tensor components to interpolate, e.g.
      64              :  * "Lapse", "Shift_x", "Shift_y", "Shift_z", "SpatialMetric_xx", etc.
      65              :  * Look into the H5 file to see what components are available.
      66              :  * \param target_points The points to interpolate to, in inertial coordinates.
      67              :  * \param extrapolate_into_excisions Enables extrapolation into excision regions
      68              :  * of the domain (default is `false`). This can be useful to fill the excision
      69              :  * region with (constraint-violating but smooth) data so it can be imported into
      70              :  * moving puncture codes. Specifically, we implement the strategy used in
      71              :  * \cite Etienne2008re adjusted for distorted excisions: we choose uniformly
      72              :  * spaced radial anchor points spaced as $\Delta r = 0.3 r_\mathrm{AH}$ in the
      73              :  * grid frame (where the excision is spherical), then map the anchor points to
      74              :  * the distorted frame (where we have the target point) and do a 7th order
      75              :  * polynomial extrapolation into the excision region.
      76              :  * \param error_on_missing_points If `true`, an error will be thrown if any of
      77              :  * the target points are outside the domain. If `false`, the result will be
      78              :  * filled with NaNs for points outside the domain (default is `false`).
      79              :  * \param num_threads The number of threads to use if OpenMP is linked in. If
      80              :  * not specified, OpenMP will determine the number of threads automatically.
      81              :  * It's also possible to set the number of threads using the environment
      82              :  * variable OMP_NUM_THREADS. It's an error to specify num_threads if OpenMP is
      83              :  * not linked in. Set num_threads to 1 to disable OpenMP.
      84              :  * \return std::vector<std::vector<double>> The interpolated data. The first
      85              :  * dimension corresponds to the selected tensor components, and the second
      86              :  * dimension corresponds to the target points.
      87              :  */
      88              : template <size_t Dim>
      89            1 : std::vector<std::vector<double>> interpolate_to_points(
      90              :     const std::variant<std::vector<std::string>, std::string>&
      91              :         volume_files_or_glob,
      92              :     const std::string& subfile_name, const ObservationVariant& observation,
      93              :     const std::vector<std::string>& tensor_components,
      94              :     const std::array<std::vector<double>, Dim>& target_points,
      95              :     bool extrapolate_into_excisions = false,
      96              :     bool error_on_missing_points = false,
      97              :     std::optional<size_t> num_threads = std::nullopt);
      98              : 
      99              : }  // namespace spectre::Exporter