Split Number into digits adding up to it.

I need to split a number into smaller integers that add up to it.

So 4 -> [0,4],[1,3],[2,2],[3,1],[4,0]

6 -> [0,6],[1,5],[2,4],[3,3]...

I know this can be done with for loops but wanted to see if there is another way.

[Stephen23]

"I need to split a number into smaller integers that add up to it. So 4 -> [0,4],[1,3],[2,2],[3,1],[4,0]"

What about [1,1,1,1],[1,1,2],[1,2,1],[2,1,1],etc., and [4]?

How many zeros are allowed? What about [0,0,0,4], [0,0,2,2], etc.?

[Alberto Lorenzo]

This is to simulate aircrafts in a collision paths so zeros and ones would not make sense. Also I have a maximum of 3 vehicles per encounters so I have some extra steps to only consider valid sets. So the only choice for 4 would be [2,2], 6 would have [2,2,2] or [3,3] where each values is the number of vehicles per encounter.

Answer 1

[Ameer Hamza]

What about

f = @(n) [0:n; n:-1:0].';

Result

>> f(4)
ans =
     0     4
     1     3
     2     2
     3     1
     4     0
>> f(6)
ans =
     0     6
     1     5
     2     4
     3     3
     4     2
     5     1
     6     0

[Alberto Lorenzo]

Vary clean and simple. Worked great!

[Ameer Hamza]

I am glad to be of help!

Answer 2

[KSSV]

n = 4 ; 
[X,Y] = meshgrid(0:n,0:n) ; 
thesum = X+Y ; 
idx = thesum==n ; 
iwant = [X(idx) Y(idx)] 

n = 6 ; 
[X,Y] = meshgrid(0:n,0:n) ; 
thesum = X+Y ; 
idx = thesum==n ; 
iwant = [X(idx) Y(idx)]