Here's a start:
clc; % Clear the command window.
fprintf('Beginning to run %s.m.\n', mfilename);
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 18;
period = 1/200000;
numSamples = 2000; % Well oversampled!
t = linspace(0, 5*period, numSamples); % Time covers 5 periods
amplitude = 7;
y = amplitude * sin(2 * pi * t / period);
plot(t, y, 'b-', 'LineWidth', 2);
grid on;
xlabel('t', 'FontSize', fontSize);
ylabel('y', 'FontSize', fontSize);
