Given the matrix
<:/~i.5 NB. 5 could be any positive integer
1 1 1 1 1
0 1 1 1 1
0 0 1 1 1
0 0 0 1 1
0 0 0 0 1
I want to generate
1 1 1 1 1
1 2 2 2 2
2 3 4 4 4
4 6 7 8 8
8 12 14 15 16
which one would expect to construct with
((+ +/),])/&.|.<:/~i.5
but then
1 1 1 1 1 6 6 6 6 5 35 35 35 34 34 208 208 207 207 207 1245 1244 1244 1244
1244
Of course I can think of all kind of solutions of which
(3 : ('z=.(1-#y)}.y';'for_k. }.i.#y do. z=.z, (k{y) + +/z end.';'z'))
<:/~i.5
I regard the most satisfactory.
Does anyone has a more elegant tacit solution then
(((+ +/),]),:^:(1=#@$))/&.|. <:/~i.5
1 1 1 1 1
1 2 2 2 2
2 3 4 4 4
4 6 7 8 8
8 12 14 15 16
R.E Boss
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