This is my code in case it is relevant. I am doing some simple
interpolation to calculate a step size for an iterative non-linear
problem. This is the test program I wrote.
int main()
{
//declare and initialise
int degree = 4;
double *x = new double[degree + 1];
double *y = new double[degree + 1];
std::vector<dolfin::uint> columns;
std::vector<double> values;
dolfin::LinearSolver linSolver;
dolfin::Matrix X(degree + 1, degree + 1);
dolfin::Vector Y(degree + 1);
dolfin::Vector A(degree + 1);
//generate test points
x[0] = 0;
y[0] = 0;
x[1] = 1;
y[1] = -2;
x[2] = 2;
y[2] = -1;
x[3] = 3;
y[3] = -2;
x[4] = 4;
y[4] = 0;
//set vector
Y.set_local(y);
//set matrix
for (int j = 0; j <= degree; j ++)
columns.push_back(dolfin::uint(j));
for (dolfin::uint row = 0; row < dolfin::uint(degree); row++){
for (int j = 0; j <= degree; j++)
values.push_back( power(x[row], (degree - j) ) );
X.setrow(row, columns, values);
values.clear();
}
//solve [X]{A} = {Y} where A is the coefficients of the polynomial
linSolver.solve(X, A, Y);
//output
for (int j = 0; j <= degree; j++)
std::cout << A[j] << std::endl;
//clean up
delete [] x;
delete [] y;
}
Any help is appreciated. Thank you.
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