Question

% Code slightly modified from Signals and Systems by Lathi MS2P4 pg 232.

How can I make this code a function? So that I can just “call” it to use it. Instead of pasting this whole thing over and over. This is just a convolution animation of two functions.

figure(1) % Create figure window and make visible on screen 
x = @(t) cos(2*pi*3*t).* u(t);
h = @(t) u(t)-u(t-1);
dtau = 0.005;
tau = -1:dtau:4;
ti = 0;
tvec = -1:0.1:5;
y = NaN*zeros(1,length(tvec)); % Pre-allocate memory
for t = tvec,
    ti = ti + 1; % Time index
    xh = x(t-tau).*h(tau);
    lxh = length(xh);
    y(ti) = sum(xh.*dtau); % Trapezoidal approximation of integral
    subplot(2,1,1)
    plot(tau,h(tau),'k-',tau,x(t-tau),'k--',t,0,'ok')
    axis([tau(1) tau(end) -2.0 2.5])
    patch([tau(1:end-1);tau(1:end-1);tau(2:end);tau(2:end)],...
        [zeros(1,lxh-1);xh(1:end-1);xh(2:end);zeros(1,lxh-1)],...
        [0.8 0.8 0.8],'edgecolor','none')
    xlabel('\tau')
    legend('h(\tau)','x(t-\tau)','t','h(\tau)x(t-\tau)')
    c = get(gca,'children');
    set(gca,'children',[c(2);c(3);c(4);c(1)]);
    subplot(2,1,2)
    plot(tvec,y,'k',tvec(ti),y(ti),'ok')
    xlabel('t')
    ylabel('y(t) = \int h(\tau)x(t-\tau) d\tau')
    axis([tau(1) tau(end) -1.0 2.0])
    grid
    drawnow
%   pause
end

Answer 1

You can use Matlab’s function , as described here

So, you have to write on the top “function yourFunctionName” and then you can call it using its name, yourFunctionName in this case.