Try this:
x1 = linspace(0, 1, 10);
y1 = rand(1, 10);
x2 = linspace(0, 1, 200);
y2 = interp1(x1, y1, x2, 'spline');
figure(1)
plot(x1, y1, 'o')
hold on
p2 = plot(x2, y2);
hold off
grid
legend(p2, 'Interpolated Data')
Experiment to get the result you want.
