# Timed plots of Particle-in-a-box?

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Cas Cas on 27 Oct 2017
I am writing some particle-in-a-box code and have it working just fine. However, I'm wondering if it is possible to time it so that perhaps it goes down from crest to trough in 2 seconds and then back up from trough to crest in 6. I tried working it out myself but I'm a bit stuck with the timings.
% Constants and variables
n = 1;
Lx = 1;
hbar = 1;
m = 1;
k = @(n) n*pi/Lx;
w = hbar*k(n)^2/2*m;
A = sqrt(2/Lx)./2;
x = linspace(0,Lx,200);
fs = 44100;
total = 6;
ratio = 0.2;
down = total/(ratio + 1);
up = total - down;
% t = linspace(0,total,500);
t = linspace(0,total,fs*total);
% Position and time functions
psi = @(x,n) A.*sin(k(n)*x);
phi = @(t) exp(-1i.*w.*t);
% Plot it.
for ii = 1:up*fs/60:up*fs
% if m<= (up/2)*fs
figure(1)
cla
plot(x, real(psi(x,n)*phi(t(ii))))
xlim([0 1])
ylim([-1.5 1.5])
drawnow
end
for m = up*fs:down*fs/60:total*fs
figure(1)
cla
plot(x, real(psi(x,n)*phi(t(m))))
xlim([0 1])
ylim([-1.5 1.5])
drawnow
% pause(0.2)
end
I used the drawnow method because I want to eventually grab the frames and make a movie. I tried to make an attempt at calculating when the ups and downs end and doing something like "if we're still going down, then go at this speed else go up at this other speed". I also tried to use the pause command but it's been tricky. Thanks in advance.