# sumc¶

## Purpose¶

Computes the sum of each column of a matrix or the sum across the second-fastest moving dimension of an L-dimensional array.

## Format¶

y = sumc(x)
Parameters:

x (matrix or array) – NxK matrix or L-dimensional array where the last two dimensions are $$NxK$$

Returns:

y (Kx1 vector or L-dimensional array) – contains the sum of each column, where the last two dimensions are $$Kx1$$.

## Examples¶

// Create a 12x1 vector containing an additive sequence
// counting by twos, from 0-22, i.e. 2, 4, 6, 8...22
x = seqa(0, 2, 12);

// Reshape the 12x1 vector 'x' into a 3x4 matrix
x = reshape(x, 3, 4);

// Sum the columns
y = sumc(x);


After the above code, the variables x and y are equal to:

     0  2  4  6
x =  8 10 12 14
16 18 20 22

24
y = 30
36
42

// Create an additive sequence from 1-24 and reshape it into
// a 2x3x4 array
a = areshape(seqa(1, 1, 24), 2|3|4);

// Sum the columns across the second fastest moving
// dimension
z = sumc(a);


a is a 2x3x4 array such that:

Plane [1,.,.]

1.0000000     2.0000000     3.0000000     4.0000000
5.0000000     6.0000000     7.0000000     8.0000000
9.0000000     10.000000     11.000000     12.000000

Plane [2,.,.]

13.000000     14.000000     15.000000     16.000000
17.000000     18.000000     19.000000     20.000000
21.000000     22.000000     23.000000     24.000000


Variable z is a 2x4x1 array equal to:

Plane [1,.,.]

15.000000
18.000000
21.000000
24.000000

Plane [2,.,.]

51.000000
54.000000
57.000000
60.000000