How can I build a matrix with an increasing number of terms in each row?

I'm trying to build a matrix which has an increasing number of summed terms in each row.

For example n = 1 would be the first row, the sum of n = 1 and n = 2 in the second row and so forth, all the way up through n = 50.

I believe the matrix should come out like

1

1 2

1 2 3

Answer 1

[Dave B]

You can't have a matrix with a different number of elements on each row, but if you wanted the sums 1, 1+2, 1+2+3,... (as you describe):

n = 1:50;
sums = n.*(n+1)/2;
sums.'

ans = 50×1

1 3 6 10 15 21 28 36 45 55

Answer 2

[Image Analyst]

If you're willing to use a cell array instead of a regular matrix, you can do this:

n = 50;
ca = cell(n, n)
for row = 1 : n
    for col = 1 : row
        ca{row, col} = sum(1:col);
    end
end

https://matlab.fandom.com/wiki/FAQ#What_is_a_cell_array.3F

The "unused" cells will still be there but they will have null inside them.