class 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;
        }
    }

    public  DirichletKernel(int n);

}