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