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$ "
      40              :       "\\dfrac{1}{x_h-x_l}(24c^2-32c^3) \\f$ for \\f$ 0 le c le 0.5 \\f$; \\f$ \\dfrac{1}{x_h-x_l} "
      41              :       "(24(1-c)^2 - 32(1-c)^3) \\f$ for \\f$ 0.5 le c le 1 \\f$, and 0.0 otherwise. Here, \\f$ c = "
      42              :       "\\frac{x-x_l}{x_h-x_l} \\f$ where \\f$x_l\\f$ and \\f$x_h\\f$ are the lower and upper bound "
      43            2 :       "for rescaling the input argument.";
      44              : 
      45            4 :   options.set_input("argument");
      46            4 :   options.set("argument").doc() = "Argument of the smooth step function";
      47              : 
      48            4 :   options.set<bool>("define_second_derivatives") = true;
      49              : 
      50            4 :   options.set_output("value");
      51            4 :   options.set("value").doc() = "Value of the smooth step function";
      52              : 
      53            4 :   options.set_buffer<TensorName<Scalar>>("lower_bound");
      54            4 :   options.set("lower_bound").doc() = "Lower bound of the argument";
      55              : 
      56            4 :   options.set_buffer<TensorName<Scalar>>("upper_bound");
      57            2 :   options.set("upper_bound").doc() = "Upper bound of the argument";
      58              : 
      59            2 :   return options;
      60            0 : }
      61              : 
      62            1 : SymmetricHermiteInterpolation::SymmetricHermiteInterpolation(const OptionSet & options)
      63              :   : Model(options),
      64            1 :     _x(declare_input_variable<Scalar>("argument")),
      65            1 :     _y(declare_output_variable<Scalar>("value")),
      66            4 :     _x0(declare_buffer<Scalar>("lb", "lower_bound")),
      67            5 :     _x1(declare_buffer<Scalar>("ub", "upper_bound"))
      68              : {
      69            1 : }
      70              : 
      71              : void
      72            3 : SymmetricHermiteInterpolation::set_value(bool out, bool dout_din, bool d2out_din2)
      73              : {
      74            3 :   const auto eps = machine_precision(_x.scalar_type()).toDouble();
      75            3 :   const auto x = clamp((_x - _x0) / (_x1 - _x0), eps, 1.0 - eps);
      76            3 :   const auto scale = 1.0 / (_x1 - _x0);
      77              : 
      78            3 :   if (out)
      79              :   {
      80            1 :     auto f_xl = 24 * x * x - 32 * x * x * x;
      81            1 :     auto f_xh = 24 * (1 - x) * (1 - x) - 32 * (1 - x) * (1 - x) * (1 - x);
      82            1 :     _y = where(x < 0.5, scale * f_xl, scale * f_xh);
      83            1 :   }
      84              : 
      85            3 :   if (dout_din)
      86              :   {
      87            1 :     auto df_xl = 48 * x - 96 * x * x;
      88            1 :     auto df_xh = -48 * (1 - x) + 96 * (1 - x) * (1 - x);
      89              : 
      90            1 :     _y.d(_x) = where(x < 0.5, scale * df_xl, scale * df_xh);
      91            1 :   }
      92              : 
      93            3 :   if (d2out_din2)
      94              :   {
      95            1 :     auto df2_xl = 48 - 192 * x;
      96            1 :     auto df2_xh = 48 - 192 * (1 - x);
      97              : 
      98            1 :     const auto zeromask = Scalar(at::logical_and(at::lt(x, 1.0 - eps), at::gt(x, eps)));
      99            1 :     _y.d(_x, _x) = zeromask * where(x < 0.5, scale * df2_xl, scale * df2_xh);
     100            1 :   }
     101            3 : }
     102              : } // namespace neml2