Probability function of people at a party.

So, you're asked to write a function that computes the probability of two people at a party having the same birthday. The probability function itself is

P(n) = 0, n = 1

P(n) = 1 - (capital pi from k = 1 to k = n - 1)(1 - k/365), 2 <=n <= 365

P(n) = 1, n >= 366

The function is used to calculate the minimum value of m (your chosen n)n for which P(m) >= q. Where q (0, 1], i.e. an arbitrary probability. The function should accept q as an input and return m as an output.Here's my code:

function [m] = Prob(q)

m = 0; %assign m initial value of 0

P = 0; %assign P a value of 0 for now so that while loop will start

while P < q %runs until P >= q

      m = m + 1; %increments m as long as condition above is true
      if m == 1 %checks first condition
          P = 0;

      elseif m >= 2 && m <= 365 %checks second condition
          S = 1; %variable that stores the product of (1 - k/365) from 1 -> m-1

          for k = 1: m - 1 
              S = S * (1 - k/365);

          P = 1 - S; %calculates P by subtracting S(the total product) from 1                                      

      else %checks third condition
        P = 1; %assigned 1 if m >= 365
      end

end
Does this seem ok? So hard to debug it when you're not actually in MATLAB.

[Image Analyst]

Why not wait until you have MATLAB running to debug it yourself rather than asking us to do it now for you?

[David]

I'm not so much asking ye to debug it yourselves as to have a quick look at the concept of the code and see if it makes general sense. I can refine it myself later on.

Answer 1

[Doug Hull]

I did not run everything, but here is a problem:

if m = 1 %checks first condition

= is a statement. == is a question.

You want the question for here. There may be other problems.

Doug

[David]

Was writing it in notepad so must've thrown that in there by mistake!