What are practical uses for STL's 'partial_sum'?

Question

What/where are the practical uses of the partial_sum algorithm in STL?

What are some other interesting/non-trivial examples or use-cases?

Answer 1

Personal Use Case: intermediate step in counting sort from CLRS:

COUNTING_SORT (A, B, k)

for i ← 1 to k do
    c[i] ← 0
for j ← 1 to n do
    c[A[j]] ← c[A[j]] + 1
//c[i] now contains the number of elements equal to i


// std::partial_sum here
for i ← 2 to k do
    c[i] ← c[i] + c[i-1]


// c[i] now contains the number of elements ≤ i
for j ← n downto 1 do
    B[c[A[i]]] ← A[j]
    c[A[i]] ← c[A[j]] - 1