Subscript indices must either be real positive integers or logicals. Error in erlang3 (line 4) erlang = lambda*exp​(-1*lambda​*xk)*(lamb​da*xk)^2/2​;

clc;
clear scr;
xk = rand(10000);
erlang = lambda*exp(-1*lambda*xk)*(lambda*xk)^2/2;
y = histogram(erlang,'Normalization','pdf');
subplot(2,1,1);
plot(xk,y);
% xlabel('X');
% ylabel ('Y');
title ('Erlang-3 Distribution');

Answer 1

[Robert]

Is there any chance you defined a variable exp before executing this code? My best guess (given the limited information provided) is that MATLAB is interpreting (-1*lambda*xk) as an indexing operation into the variable exp, which could happen if exp is not pointing to the function as you expect but is instead pointing to a variable.

[vanitha usika]

exp is just define the exponential variable generally for exponential we don't need to define exp

[Robert]

Exactly; however, there is nothing stopping you from replacing exp for example

clear
exp(1)
exp(2)
exp = 42
exp(1)
exp(2)

As Walter suggested, you can use the command which to ask MATLAB from where it is getting exp

clear
which exp
exp = 42
which exp

Answer 2

[Star Strider]

The most likely possibility is that somewhere in your code you have a variable called ‘exp’. The solution is to find it and name it something else.

Answer 3

[Walter Roberson]

At the command prompt command

dbstop if error

and run the code. When (if) it stops with the error, please report the results of

which exp