aUCBLogo Demos and Tests / det

to det
   pr "Determinant
   ar = {{1 0 2 -1}{3 -2 6 4}{5 4 3 0}{2 2 -5 6}} ; -> det=-132
   m=count ar
   pr (se "Ordnung= m)
   pr ar
   br=(mdArray (se m-1 m-1) 1)
   for [i 1 m-1] [for [j 1 m-1] [setB i j 0] ]
   q=1
   for [n m 2 -1]
   [   z=0
      ifElse (readA 1 1) == 0 [qq=1][qq=(1/(readA 1 1))^(n-2)]
      q=q*qq ;cs
      pr (se "from_n= n "to_n= n-1)
      pr (se "qq qq "q= q)

      for [i 2 n]
      [   for [j 2 n]
         [   z=z+1
            a=(readA 1 1) * (readA i j) - (readA i 1) * (readA 1 j)
            (setB i-1 j-1 a)
            pr (se "a( i-1 j-1 ")= a )
            if n == 2
            [   (pr)
               pr "Result:
               pr (se "a= a "; "q= q "; "Det=a*q= q*(readB i-1 j-1))
               stop
            ]
            if z == (n-1)^2 [(pr) pr "(nextpage)]
         ] ; next j
         (pr)
      ] ; next i

      for [i 1 n-1]
      [
      for [j 1 n-1]
      [(setA i j (readB i j))]
      ] ; next i
   ] ; next n

   to readA ia ib
      op ri (se ia ib) ar
   end

   to readB ia ib
      op ri (se ia ib) br
   end

   to ri iList mat ; read item
      op mdItem iList mat
   end

   to setA ia ib val
      si (se ia ib) ar val
   end

   to setB ia ib val
      si (se ia ib) br val
   end

   to si iList mat val ; set item
      mdSetItem iList mat val
   end
end