RSUM

Rsum is a term that appears in several different domains and does not have a single, universally accepted meaning. In computing and data analysis, rsum is commonly used as an informal shorthand for running sum or prefix sum, which is the cumulative total of a sequence of numbers as it is processed from start to end. If a sequence a1, a2, ..., an is given, the running sum at position k is sk = a1 + a2 + ... + ak. Running sums are used to efficiently compute cumulative totals, to implement algorithms such as prefix sums in parallel processing, and to construct cumulative statistics in time series data.

In programming and scripting, rsum is often used as a variable or function name to represent a running total. Its exact behavior depends on the surrounding code, so its meaning can vary between languages, libraries, and projects.

Beyond mathematics and programming, RSUM may appear as an acronym in specific organizations, datasets, or software projects. Because it is not standardized, readers should rely on context to determine the intended meaning. In general, if you encounter rsum, consider whether it refers to a cumulative quantity, a label for a helper function, or an acronym tied to a particular domain.

See also: prefix sum, cumulative sum, running total, inclusive scan.