Sinewave generator based on the second answer of http://dsp.stackexchange.com/questions/971/how-to-create-a-sine-wave-generator-that-can-smoothly-transition-between-frequen

generate_sinewave.m

clearvars
clc
close all

fs = 8000;
fc = 440;
omega = exp(1j*2*pi*fc/fs);
amplitude = 0.5;

signal_time = 1; % in seconds
signal_length = floor(fs*signal_time);

z = zeros(signal_length,1);
z(1) = amplitude;

exponent = 2;
freq_value = exp(1j*linspace(0,pi^(1/exponent),signal_length).^exponent);
for i=2:signal_length
    z(i) = z(i-1)*freq_value(i);
    % z(i) = z(i-1)*omega;
end

audiowrite('sinewave.wav',real(z),fs)

% plot(real(z))
% hold on
% plot(imag(z))