Ex_01.cpp

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#include <fstream> // To output data to files
#include <iostream>
#include <sis.hpp>

using namespace std;

int main() {
  using namespace sis;
  N = 63; // sis::N, Defined in sis.hpp. This specifies no. of Chebyshev
          // coefficients
  sis_setup();

  LinopMat<complex<double> > Lmat(1, 1);
  Linop<double> D2(2), D1(1), D0(0); // Linops with highest order 2, 1 and 0.

  D2.coef << 1.0, 0.0, 0.0; // for (1.0 * D2 + 0.0 * D1 + (0.0) )v
  D1.coef << 1.0, 0.0;
  D0.coef << 1.0;

  //Chebfun<complex<double> > tempfun;
  //tempfun.v = 0.0;
  //tempfun.v[1] = complex<double>(1.0,1.0);
  //tempfun.dct_flag = SIS_CHEB_SPACE;
  //tempfun.c2p();
  //cout << tempfun << endl;
  //tempfun.p2c();
  //cout << tempfun << endl;
  //exit(1);

  // for operator D2v - 4 v
  Lmat << D2 - 4.0 * D0;

  // Specify boundary conditions via BcMat:
  BcMat<complex<double> > bcs(2, 1); 
      // Two boundary conditions in total, on one variable

  // Some mixed boundary condition:
   bcs.L << D0 + 4.0*D1, // Operator
           D0 - 5.0*D1;
  bcs.eval << 1.0,       // Evaluation points 
              -1.0;
  bcs.vals << 2.0,       // Values at end point 
      3.0;          

  // Construct forcing, forc = 1 - y^2
  ChebfunMat<complex<double> > forc(1, 1); // 1 by 1 ChebfunMat
  forc << 1.0 - y * y;                     // y is defined in sis::y

  // Solve, by replacing the forcing as the solution.
  forc = linSolve(Lmat, bcs, forc);

  // Write to file to plot, need only the real part:
  ofstream outf;
  outf.open("data/Ex_01.txt");
  Eigen::MatrixXd temp(N + 1, 2);
  temp << yEigen, forc(0,0).evr();
  outf << temp;
  // note that sis::yEigen is the same as y, but of type Eigen Matrix,
  outf.close();
  return 0;
}