sum

Scilab Function
Last update : 25/04/2007

sum - sum (row sum, column sum) of vector/matrix entries

### Calling Sequence

  `y=sum(x)`
  `y=sum(x,'r') or y=sum(x,1)`
  ``
  `y=sum(x,'c') or y=sum(x,2)`
  ``
  `y=sum(x,'m')`

### Parameters

- `x` : vector or matrix (real, complex, sparse or polynomial)
- `y` : scalar or vector

### Description

For a vector or a matrix `x` , `y=sum(x)` returns in the scalar `y` the sum of all the entries of `x` .

`y=sum(x,'r')` (or, equivalently, `y=sum(x,1)` ) is the rowwise sum: `y(j)= sum(x(:,j))` . `y` is a row vector

`y=sum(x,'c')` (or, equivalently, `y=sum(x,2)` ) is the columnwise sum. It returns in each entry of the column vector `y` the sum : `y(i)= sum(x(i,:))` )).

`y=sum(x,'m')` is the sum along the first non singleton dimension of `x` (for compatibility with Matlab).

### Examples

    A=[1,2;3,4];
    trace(A)-sum(diag(A))
    sum(A,'c')-A*ones(2,1)
    sum(A+%i)
    A=sparse(A);sum(A,'c')-A*ones(2,1)
    s=poly(0,'s');
    M=[s,%i+s;s^2,1];
    sum(M),sum(M,2)

### See Also

`cumsum` , `prod` ,