SAC Stands for Single Assignment C Programming Languages It is Functional Programming Language used for designing numerical application. It used array processing, so runtime of program in time and memory consumption is not much.
The iota function means yields a vector (a one-dimensional array) of n elements with the values 0 to n-1. Adding the value 1 to this vector yields the n-element vector with the numbers 1 to n. Computing the product of all elements of this vectors yields the factorial of n.
Good programming tutorial on SAC Language can be access using following Books: