cummax() function in R Language is used to calculate the cumulative maxima of the values of vector passed as arguments.

Syntax: cummax(x)

Parameters:
x: numeric object

Example 1:

Output:

[1] 6 6 6 6 6
[1] -2 -2 -2 -2 -2
[1] 3.8 3.8 3.8

Example 2:

Output:

[1] 5 5 5 6 6 6
[1] -4  6  6

Since, the maxima is calculated for the values in decreasing order and hence the above code shows two cumulative values for vectors.