There are four generalized functions in the <numeric> header that follow the same conventions as those in <algorithm>. Each of them is overloaded: one signature for common default operations, and a second for fully general operations. Their names are self-explanatory to anyone who works with numerics on a regular basis:

Here is a simple example of the two forms of accumulate.

 int ar[50];
 int someval = somefunction();
 // ...initialize members of ar to something...
 int sum = std::accumulate(ar,ar+50,0);
 int sum_stuff = std::accumulate(ar,ar+50,someval);
 int product = std::accumulate(ar,ar+50,1,std::multiplies<int>());
 

The first call adds all the members of the array, using zero as an initial value for sum. The second does the same, but uses someval as the starting value (thus, sum_stuff == sum + someval). The final call uses the second of the two signatures, and multiplies all the members of the array; here we must obviously use 1 as a starting value instead of 0.

The other three functions have similar dual-signature forms.