# MATLAB question-factorial

1. Oct 22, 2011

### Bassalisk

So I am trying to plot the birthday problem.

Number of people vs chance not to have the same birthday.

I know the analytical form

$P(n)={\Large\frac{365\cdot 364\cdot 363...(365-n+1)}{365^{n}}}$

problem is, matlab is giving me this, when I try to put that into code.

[PLAIN]http://pokit.org/get/e8cbb0974a4b30d349d554c27ab0f537.jpg [Broken]

And thats only trying to realise the top part of the fraction.

I am trying to get this result.

Source wikipedia.

Thank you.

Last edited by a moderator: May 5, 2017
2. Oct 22, 2011

### Dr Transport

looks like you are not dividing by 365 to the nth power

3. Oct 23, 2011

### Bassalisk

Still he is giving me infinity. I think he calculates factorial first, then to the nth, then divides that and still gets infinity

4. Oct 23, 2011

### MATLABdude

Unfortunately, MATLAB has maxima on both integers and floating point numbers:
http://www.mathworks.com/help/techdoc/ref/intmax.html
http://www.mathworks.com/help/techdoc/ref/realmax.html

I believe that both are exceeded by the calculations that you're trying to make in the numerator and denominator.

However, I believe that you can do this recursively (i.e. start with n=0, and use this result to generate n=1, use that result to generate n=2, etc.)
http://en.wikipedia.org/wiki/Recursion_(computer_science)

5. Oct 23, 2011

### Bassalisk

My hero <3 Thank you!