I don't know what is in makedist
, but Matlab has a powerful tool called find
which will seek out what you need.
In your case, if I had to guess, you can do
x(find(cdf_normal >= 0.2,1))
to get your desired data point x.
Basically it searches cdf_normal for the first occurrence of the correct statement, returns the index, then displays the value if x which corresponds to that index.