Line data    Source code

       1              : // Copyright 2024, UChicago Argonne, LLC
       2              : // All Rights Reserved
       3              : // Software Name: NEML2 -- the New Engineering material Model Library, version 2
       4              : // By: Argonne National Laboratory
       5              : // OPEN SOURCE LICENSE (MIT)
       6              : //
       7              : // Permission is hereby granted, free of charge, to any person obtaining a copy
       8              : // of this software and associated documentation files (the "Software"), to deal
       9              : // in the Software without restriction, including without limitation the rights
      10              : // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
      11              : // copies of the Software, and to permit persons to whom the Software is
      12              : // furnished to do so, subject to the following conditions:
      13              : //
      14              : // The above copyright notice and this permission notice shall be included in
      15              : // all copies or substantial portions of the Software.
      16              : //
      17              : // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
      18              : // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
      19              : // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
      20              : // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
      21              : // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
      22              : // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
      23              : // THE SOFTWARE.
      24              : 
      25              : #include "neml2/models/SymmetricHermiteInterpolation.h"
      26              : #include "neml2/tensors/functions/clamp.h"
      27              : #include "neml2/tensors/functions/where.h"
      28              : #include "neml2/tensors/assertions.h"
      29              : 
      30              : namespace neml2
      31              : {
      32              : register_NEML2_object(SymmetricHermiteInterpolation);
      33              : 
      34              : OptionSet
      35            2 : SymmetricHermiteInterpolation::expected_options()
      36              : {
      37            2 :   OptionSet options = Model::expected_options();
      38            2 :   options.doc() =
      39              :       "Define the symmetric Hermite interpolation function, taking the form of \\f$ (3c^2-4c^3) "
      40              :       "\\f$ for \\f$ 0 le c le 0.5 \\f$; \\f$ 3(1-c)^2 - 4(1-c)^3 \\f$ for \\f$ 0.5 le c le 1 "
      41              :       "\\f$, and 0.0 otherwise. Here, \\f$ c = \\frac{x-x_l}{x_h-x_l} \\f$ where \\f$x_l\\f$ and "
      42            2 :       "\\f$x_h\\f$ are the lower and upper bound for rescaling the input argument.";
      43              : 
      44            4 :   options.set_input("argument");
      45            4 :   options.set("argument").doc() = "Argument of the smooth step function";
      46              : 
      47            4 :   options.set<bool>("define_second_derivatives") = true;
      48              : 
      49            4 :   options.set_output("value");
      50            4 :   options.set("value").doc() = "Value of the smooth step function";
      51              : 
      52            4 :   options.set_buffer<TensorName<Scalar>>("lower_bound");
      53            4 :   options.set("lower_bound").doc() = "Lower bound of the argument";
      54              : 
      55            4 :   options.set_buffer<TensorName<Scalar>>("upper_bound");
      56            2 :   options.set("upper_bound").doc() = "Upper bound of the argument";
      57              : 
      58            2 :   return options;
      59            0 : }
      60              : 
      61            1 : SymmetricHermiteInterpolation::SymmetricHermiteInterpolation(const OptionSet & options)
      62              :   : Model(options),
      63            1 :     _x(declare_input_variable<Scalar>("argument")),
      64            1 :     _y(declare_output_variable<Scalar>("value")),
      65            4 :     _x0(declare_buffer<Scalar>("lb", "lower_bound")),
      66            5 :     _x1(declare_buffer<Scalar>("ub", "upper_bound"))
      67              : {
      68            1 : }
      69              : 
      70              : void
      71            3 : SymmetricHermiteInterpolation::set_value(bool out, bool dout_din, bool d2out_din2)
      72              : {
      73            3 :   const auto eps = machine_precision(_x.scalar_type()).toDouble();
      74            3 :   const auto x = clamp((_x - _x0) / (_x1 - _x0), eps, 1.0 - eps);
      75              : 
      76            3 :   if (out)
      77              :   {
      78            1 :     auto f_xl = 3 * x * x - 4 * x * x * x;
      79            1 :     auto f_xh = 3 * (1 - x) * (1 - x) - 4 * (1 - x) * (1 - x) * (1 - x);
      80            1 :     _y = where(x < 0.5, f_xl, f_xh);
      81            1 :   }
      82              : 
      83            3 :   if (dout_din)
      84              :   {
      85            1 :     auto df_xl = 6 * x - 12 * x * x;
      86            1 :     auto df_xh = -6 * (1 - x) + 12 * (1 - x) * (1 - x);
      87              : 
      88            1 :     _y.d(_x) = where(x < 0.5, df_xl, df_xh);
      89            1 :   }
      90              : 
      91            3 :   if (d2out_din2)
      92              :   {
      93            1 :     auto df2_xl = 6 - 24 * x;
      94            1 :     auto df2_xh = 6 - 24 * (1 - x);
      95              : 
      96            1 :     const auto zeromask = Scalar(at::logical_and(at::lt(x, 1.0 - eps), at::gt(x, eps)));
      97            1 :     _y.d(_x, _x) = zeromask * where(x < 0.5, df2_xl, df2_xh);
      98            1 :   }
      99            3 : }
     100              : } // namespace neml2