int main(){
int r1,c1,r2,c2,arr1[10][10],arr2[10][10],mult[10][10];
again:
printf("enter the row and column for first matrix:\n");
scanf("%d %d", &r1,&c1);
printf("enter the row and column for second matrix:\n");
scanf("%d %d", &r2,&c2);
if(c1!=r2){
printf("Error! rows or column of first matrix is not equal to row and column of second matrix.Enter Again!\n");
goto again;
}
matrix_form(arr1,arr2,r1,c1,r2,c2);
multiplication(arr1,arr2,r1,c1,r2,c2,mult);
display(mult,r1,c2);
return 0;
}
const iTEBD<Tensor>
evolve_itime(iTEBD<Tensor> psi, const Tensor &H12,
double dt, tensor::index nsteps,
double tolerance, tensor::index max_dim,
tensor::index deltan, int method,
std::vector<double> *energies,
std::vector<double> *entropies)
{
static const double FR_param[5] =
{0.67560359597983, 1.35120719195966, -0.17560359597983, -1.70241438391932};
Tensor eH12[4];
//int method = 2;
switch (method) {
case 1:
/* Second order Trotter expansion */
eH12[1] = linalg::expm((-dt/2) * H12);
case 0:
/* First order Trotter expansion */
eH12[0] = linalg::expm((-dt) * H12);
break;
default:
/* Fourth order Trotter expansion */
for (int i = 0; i < 4; i++) {
eH12[i] = linalg::expm((-dt*FR_param[i]) * H12);
}
}
Tensor Id = Tensor::eye(H12.rows());
double time = 0;
psi = psi.canonical_form();
double E = energy(psi, H12), S = psi.entropy();
if (energies)
energies->push_back(E);
if (entropies)
entropies->push_back(S);
if (!deltan) {
deltan = 1;
}
std::cout.precision(5);
std::cout << nsteps << ", " << dt << " x " << deltan
<< " = " << dt * deltan << std::endl;
std::cout << "t=" << time
<< ";\tE=" << E << "; dE=" << 0.0
<< ";\tS=" << S << "; dS=" << 0.0
<< ";\tl=" << std::max(psi.left_dimension(0),
psi.right_dimension(0))
<< std::endl
<< "l = " << matrix_form(real(psi.left_vector(0)))
<< std::endl;
for (size_t phases = (nsteps + deltan - 1) / deltan; phases; phases--) {
for (size_t i = 0; (i < deltan); i++) {
switch (method) {
case 0:
psi = psi.apply_operator(eH12[0], 0, tolerance, max_dim);
psi = psi.apply_operator(eH12[0], 1, tolerance, max_dim);
break;
case 1:
psi = psi.apply_operator(eH12[1], 0, tolerance, max_dim);
psi = psi.apply_operator(eH12[0], 1, tolerance, max_dim);
psi = psi.apply_operator(eH12[1], 0, tolerance, max_dim);
break;
default:
psi = psi.apply_operator(eH12[0], 0, tolerance, max_dim);
psi = psi.apply_operator(eH12[1], 1, tolerance, max_dim);
psi = psi.apply_operator(eH12[2], 0, tolerance, max_dim);
psi = psi.apply_operator(eH12[3], 1, tolerance, max_dim);
psi = psi.apply_operator(eH12[2], 0, tolerance, max_dim);
psi = psi.apply_operator(eH12[1], 1, tolerance, max_dim);
psi = psi.apply_operator(eH12[0], 0, tolerance, max_dim);
}
time += dt;
}
psi = psi.canonical_form();
double newE = energy(psi, H12);
double newS = psi.entropy();
if (energies)
energies->push_back(newE);
if (entropies)
entropies->push_back(newS);
std::cout << "t=" << time
<< ";\tE=" << newE << "; dE=" << newE-E
<< ";\tS=" << newS << "; dS=" << newS-S
<< ";\tl=" << std::max(psi.left_dimension(0),
psi.right_dimension(0))
<< std::endl
<< "l = " << matrix_form(real(psi.left_vector(0)))
<< std::endl;
E = newE;
S = newS;
}
return psi;
}
scalar DefaultMatrixFormSurf::value(int n, double *wt, Func<scalar> *u_ext[], Func<double> *u, Func<double> *v,
Geom<double> *e, ExtData<scalar> *ext) const {
return matrix_form(n, wt, u_ext, u, v, e, ext);
}
