Can Matlab Factorial a Large Number?

Hello, I'm solving a problem of probability and need to calculate a factorial(365), but the factorial function in Matlab gives me a result of Inf. Can anyone know how to use the factorial function to calculate a large number such as factorial(365),factorial(321) ? Thank you! Ben

Answer 1

[James Tursa]

You could use one of these FEX submissions by John D'Errico:

https://www.mathworks.com/matlabcentral/fileexchange/22725-variable-precision-integer-arithmetic

https://www.mathworks.com/matlabcentral/fileexchange/36534-hpf-a-big-decimal-class

Also, consider reformulating your calculation to avoid these large numbers. E.g., I am guessing that this large factorial is part of an expression that has other large factorials as well. Look for ways to "cancel" portions of the calculation so that smaller calculations remain.

[Ben Le]

Thank you James! Your answer is very interesting. Wow! There is so many things I need to learn prior to getting the answer. I thought there is a simple function that I can use to factorial a large integer number. Thank you again for pointing me to the right section I want to know. Ben

Answer 2

[Image Analyst]

The FAQ http://matlab.wikia.com/wiki/FAQ#How_does_one_compute_a_factorial.3F says to use gamma().

[Ben Le]

Hello Image Analyst, The link is interesting. Wow! There is so many things I need to learn prior to getting the answer. I thought there is a simple function that I can use to factorial a large integer number. Thank you again for pointing me to the right section I want to know. Ben