I need a bimodal distribution. Since I could not find any among the ones provided by Maple, I created a simple one:
U := Distribution(PDF = (proc (t) options operator, arrow; piecewise(t < -5, 0, t < 5, -(1/2000)*t^4+(9/1000)*t^2+7/80, 0) end proc)):
X := RandomVariable(U):
#Plotting PDF and CDF works fine:
plot(PDF(X, t), t = -infinity .. infinity);
plot(CDF(X, t), t = -infinity .. infinity)
However, plotting the quantile function does not work:
plot(Quantile(X, z), z = 0 .. 1);
it has a decreasing part for z<1/2 and a discontinuity at z=1/2.
I can plot it correctly as
plot('Quantile'(X, z), z = 0 .. 1);
but I wonder why the first option does not work for such a simple distribution.