SUM Sum Function
Section: Elementary Functions
UsageComputes the summation of an array along a given dimension. The general syntax for its use is
y = sum(x,d)
x is an
n-dimensions array of numerical type.
The output is of the same numerical type as the input. The argument
d is optional, and denotes the dimension along which to take
the summation. The output
y is the same size as
that it is singular along the summation direction. So, for example,
x is a
3 x 3 x 4 array, and we compute the summation along
d=2, then the output is of size
3 x 1 x 4.
Function InternalsThe output is computed via
d is omitted, then the summation is taken along the
first non-singleton dimension of
ExampleThe following piece of code demonstrates various uses of the summation function
--> A = [5,1,3;3,2,1;0,3,1] A = 5 1 3 3 2 1 0 3 1
We start by calling
sum without a dimension argument, in which
case it defaults to the first nonsingular dimension (in this case,
along the columns or
d = 1).
--> sum(A) ans = 8 6 5
Next, we take the sum along the rows.
--> sum(A,2) ans = 9 6 4