I want to compute delta but i do not want to show result for delta. i know i need to put

delta := unassign('delta');

but i do not know where to put, i try and error so many times but the answer still the same.

the answer should be in marix form 2x2

[-δD11 0 ]

[0 D22]

>derivation := proc (A, n)

local i, j, k, t, s1, m, D, sols, eqns, BChange, delta; eqns := {}; D := matrix(n, n); BChange := matrix(n, n);

for i to n do

for j to n do

for m to n do

s1 := sum(0*A[i, j, k]*D[m, k], k = 1 .. n)-(sum(A[k, j, m]*D[k, i]+delta*A[i, k, m]*D[k, j], k = 1 .. n));

eqns := `union`(eqns, {s1})

end do

end do

end do;

sols := [solve(eqns)];

delta := unassign('delta');

t := nops(sols);

for i to t do

for j to n do

for k to n do

BChange[k, j] := subs(sols[i], D[k, j])

end do

end do;

print("BChange:=", BChange)

end do

end proc

> AS1 := array(sparse, 1 .. 2, 1 .. 2, 1 .. 2, [(1, 1, 2) = 1]);

> derivation(AS1, 2);