### I want to display the origin on the graph.

var('d n')

d = 2; n = 1;

psi(x) = sqrt(2.0/d)*sin(n*pi*x/d)

graph = plot( (abs(psi(x)))^2 , 0, d, figsize=5, axes_labels=['$x$', '$|\psi_{1}(x)|^2$'])
(graph).show()

I'm displaying the graph using the above method, but I can't display the origin.