d6/d6a/Example_26_Jacobian_Tape_Readers.html

#include <codi.hpp>

#include <iostream>


int main(int nargs, char** args) {

  // Step 1: Match the Real type with the stored type

  using Real = codi::RealReverse;

  using Tape = typename Real::Tape;

  using Identifier = typename Real::Identifier;


  const std::string directory = "documentation/generated_files/";


  // Step 2: Use the file name of the .txt or .dat file to restore the tape

  auto reader = codi::readTapeFile<Real>(directory + "jacobian_linear_text.txt");


  // Step 3: Get the restored tape and the IO

  Tape& tape = reader->getTape();

  std::vector<Identifier> const& x_id = reader->getInputs();

  std::vector<Identifier> const& y_id = reader->getOutputs();


  // Step 4: Seed the restored IO and evaluate the tape

  tape.gradient(y_id[0]) = 1.0;


  tape.evaluate();


  // Step 5: View the results

  std::cout << "df/dx[0] = " << tape.getGradient(x_id[0]) << std::endl;

  std::cout << "df/dx[1] = " << tape.getGradient(x_id[1]) << std::endl;


  return 0;

}