Forward difference: Difference between revisions

=={{header|Picat}}==

<lang Picat>go =>

L = [90, 47, 58, 29, 22, 32, 55, 5, 55, 73],

foreach(I in 1..L.length-1)

println([d=I,diffi(L,I)])

end,

nl,

% All differences (a sublist to save space)

println(alldiffs(L[1..6])),

nl.

% Difference of the list

diff(L) = Diff =>

Diff = [L[I]-L[I-1] : I in 2..L.length].

% The i'th list difference

diffi(L,D) = Diff =>

Diff1 = L,

foreach(_I in 1..D)

Diff1 := diff(Diff1)

end,

Diff = Diff1.

% all differences

alldiffs(L) = Diffs =>

Diffs1 = [],

Diff = L,

foreach(_I in 1..L.length-1)

Diff := diff(Diff),

Diffs1 := Diffs1 ++ [Diff]

end,

Diffs = Diffs1.</lang>

Output:

<pre>[d = 1,[-43,11,-29,-7,10,23,-50,50,18]]

[d = 2,[54,-40,22,17,13,-73,100,-32]]

[d = 3,[-94,62,-5,-4,-86,173,-132]]

[d = 4,[156,-67,1,-82,259,-305]]

[d = 5,[-223,68,-83,341,-564]]

[d = 6,[291,-151,424,-905]]

[d = 7,[-442,575,-1329]]

[d = 8,[1017,-1904]]

[d = 9,[-2921]]

[[-43,11,-29,-7,10],[54,-40,22,17],[-94,62,-5],[156,-67],[-223]]</pre>