Sumj

Sumj is not a standard mathematical or computational term; in practice, it appears as a variable name or a concatenation of "sum" and the index variable "j." Its meaning depends on context.

In mathematics, the conventional notation for summation uses the symbol ∑ with an index, typically written as sum over j or ∑_j f(j). The string "sumj" by itself is not conventional notation, though some informal notes or software labels may use it as a label or function name.

In programming, sumj is commonly used as an identifier for a running total associated with an index j. Example in pseudocode: sumj = 0; for j in 1..n do sumj = sumj + a[j] end. Here sumj stores the cumulative sum of the array elements a[j]. In other contexts, sumj may represent a partial sum across a subset indexed by j or serve as a loop variable name.

Etymology and usage: The term arises from combining "sum" with the index variable "j" and is not standardized. For mathematical writing, clearer practice is to write "sum over j" or "sum_j" with an explicit summation sign. In programming, use descriptive variable names such as total, partial_sum, or cumulative to avoid ambiguity.

See also: Summation, Sum, Accumulator, Index variable, Partial sums, Loop.