### 7.4.21 Inverse distribution functions: icdf

The icdf command will take as arguments the name of a
probability distribution, along with any needed parameters, and return
an expression for the inverse cumulative distribution function. This
is typically most useful if you evaluate the inverse cumulative
function at a specific value by adding it as an argument. If you enter

icdf(normald,0,0.5,0.975)

you will get

0.97998199227