# sum

## Purpose

Sum of elements.

## Synopsis

    y = sum(X)

## Description

`y = sum(X)`, where `X` is a matrix, returns a row `y` vector with the sum over each column. If `X` is a vector, `y` is the sum of the elements of `X`.

## Examples

The magic square of order 3 is

    M = magic(3)

    M =
         8    1    6
         3    5    7
         4    9    2

This is called a magic square because the sum of the elements in each column is the same.

    sum(M) =
         15    15    15

And the sum of the elements in each row, which can be obtained by transposing twice, is the same.

    sum(M')' =
         15
         15
         15

## See Also

    cumsum, prod, trace

(c) Copyright 1994 by The MathWorks, Inc.