DirichletKernel implements IRealFunction { @Override public double fn(final double x) { double x2 = x * .5; if (mpi(x2)) { return mc_; } else { return (Math.sin(m_ * x2) / Math.sin(x2)) / TWOPI; } } DirichletKernel(int n); int getN(); @Override double fn(final double x);  }
@Test public void testSomeMethod() { int N=180; DirichletKernel dk=new DirichletKernel(N); double step=Math.PI*2/N; double z=0; for (int i=1; i<20; ++i){ double k=dk.fn(step*i); z+=k*k*step*Math.PI*2; } }