How to plot Lame curves in octave or matlab?

Question

MATLAB

Hello! I'm trying to draw Lame curves in octave like here , but only one branch is obtained. Tell me what I'm doing wrong?

% Кривые Ламе
n = 0.5
a = 1.0
b = 1.0
f = 0:pi/180:pi/2
x = a*cos(f).^(2/n)
y = b*sin(f).^(2/n)
figure()
plot(x, y)
grid on
axis equal
xlab = xlabel('Ось абсцисс Х');
ylab = ylabel('Ось ординат Y');
title('Кривые Ламе');

Answer 1

f = 0:pi/180:2*pi