e1 = log(floor(t))*cos(t)
e2 = log(floor(t))*sin(t)
plot_parametric(e1, e2, (t, 1, 4*pi),
    exclude=list(range(1, 13)), grid=False)
# Expected:
## Plot object containing:
## [0]: parametric cartesian line: (log(floor(t))*cos(t), log(floor(t))*sin(t)) for t over (1, 4*pi)