test_tanh2.m

software to find the threshold of an LDPC code in a Gaussian channel

function y = test_tanh2(delta,K,v_fx,lpad)

% lpad is the extra amount calculated on either side, to avoid truncation

y = zeros(1,K + 2*lpad + 1);
x = 0:delta:(delta*K);

for zi = (-1*lpad*delta):delta:(delta*(K+lpad))

	index_zi = round(zi/delta) + lpad + 1;

	if (zi < 10)
		func = 1 - tanh(x/2).^exp(zi);
	else
		func = 1 - exp(-2*exp(-1*x + zi));
	end

	y(index_zi) = sum(func.*v_fx);

end