Geometric progression is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed non-zero number called the common ratio.
If module of common ratio is greater than 1 progression shows exponential growth of terms towards infinity, if it is less than 1, but not zero, progression shows exponential decay of terms towards zero.
N-th term of the progression is found as
Partial sum to n
where q is not equal to 1
For q =1
The number of terms in infinite geometric progression will approach to infinity . Sum of infinite geometric progression can only be defined if common ratio is at the range from -1 to 1 inclusive.