Computes the summation of an array along a given dimension. The general syntax for its use is
y = sum(x,d)
where 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 x, except
that it is singular along the summation direction. So, for example,
if x is a 3 x 3 x 4 array, and we compute the summation along
dimension d=2, then the output is of size 3 x 1 x 4.
The output is computed via
If
d is omitted, then the summation is taken along the
first non-singleton dimension of x.
The following piece of code demonstrates various uses of the summation function
--> A = [5,1,3;3,2,1;0,3,1]
A =
<int32> - size: [3 3]
Columns 1 to 3
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 =
<int32> - size: [1 3]
Columns 1 to 3
8 6 5
Next, we take the sum along the rows.
--> sum(A,2)
ans =
<int32> - size: [3 1]
Columns 1 to 1
9
6
4