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+--- Thread: Cofactors and adjoint matrix (/thread-4076.html)
Cofactors and adjoint matrix - salvomic - 06-04-2015 08:06 PM
hi,
this code doesn't run:
Code:
minor();
EXPORT cofactors(m)
BEGIN
local tempmat, cofact, r, c, j, k;
r:=rowDim(m);
c:=colDim(m);
cofact:= MAKEMAT(0,r,c);
tempmat:= m;
FOR j FROM 1 TO r DO
FOR k FROM 1 to c DO
cofact:= minor(tempmat, j, k);
tempmat(j,k):= cofact;
END; // inner for
END; //for
RETURN tempmat;
END;
minor(mat, r,c)
BEGIN
mat:= delrows(mat,r);
mat:= delcols(mat,c);
RETURN mat;
END;
EXPORT adj(m)
BEGIN
local ad;
ad:= cofactors(m);
RETURN TRN(ad);
END;Is it not possible to have a matrix as item od another matrix?
I think the problem is in the line < tempmat(j,k):= cofact; >, in fact...
Any help?
Salvo
RE: Cofactors and adjoint matrix - salvomic - 06-04-2015 09:00 PM
ok, found!
this should run.
It returns both cofactors and adj (adjoint, transpose of cofactors):
Code:
minor();
EXPORT cofactors(m)
BEGIN
local tempmat, cofact, deter;
local r, c, j, k;
r:=rowDim(m);
c:=colDim(m);
cofact:= MAKEMAT(0,r,c);
tempmat:= m;
FOR j FROM 1 TO r DO
FOR k FROM 1 to c DO
cofact:= minor(m, j, k);
deter:= ((-1)^(j+k)) * det(cofact);
tempmat(j,k):= deter;
END; // inner for
END; //for
RETURN tempmat;
END;
minor(mat, r,c)
BEGIN
mat:= delrows(mat,r);
mat:= delcols(mat,c);
RETURN mat;
END;
EXPORT adj(m)
BEGIN
local ad;
ad:= cofactors(m);
RETURN TRN(ad);
END;