Do you mean like this:
r = rand;
if r < .5
% 50% probability between 0m to 25m
elseif r < 0.6
% 10% probability between 25m to 50m.
elseif r < 0.65
% 5% probability between 50m to 75m.
elseif r < 0.85
% 20% probability between 0m to 50m.
elseif r < 0.95
% 10% probability between 50m to 150m.
else
% 5% probability between 150m to 200m.
end
You get a random number and then test it. You will go into the respective blocks of the "if" with the designated probabilities. Then inside the block you can do whatever you want, such as set the altitude or change in altitude or whatever.
