use math.la: vector, matrix, scalar
use math.la.inversion: det, inv
use math.rational: rat
use sys: exit

function error(A)
   print("Error in test-la-inv:\n",A)
   exit(1)
end

function random_matrix(m,n,rng)
   return matrix(*rng.chunks(n).list(m))
end

function check(n,N,a,b)
   E = scalar(n,1,0)
   for k in 1..N
      A = random_matrix(n,n,rand(a..b)).map(rat)
      # print(A)
      if det(A)!=0
         if A*inv(A)!=E
            error(A)
         end
      end
   end
end

check(2,400,-10,10)
check(3,200,-10,10)
check(4,100,-10,10)
check(5,40,-10,10)
check(6,20,-10,10)