Cofactors and adjoint matrix - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- 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;```