a

a =

     5     7     6     5
     7    10     8     7
     6     8    10     9
     5     7     9    10

b

b =

    23
    32
    33
    31

r=a*x-b

r =

   1.0e-04 *

  -0.14999999997656
  -0.11000000000649
  -0.08000000001118
  -0.14999999997656

rr=norm(r, inf)

rr =

     1.499999999765578e-05

relr=rr/33

relr =

     4.545454544744175e-07

x

x =

   0.99941700000000
   1.00035000000000
   1.00015000000000
   0.99991000000000

x-1

ans =

   1.0e-03 *

  -0.58300000000000
   0.35000000000007
   0.15000000000009
  -0.09000000000003

rele=norm(x-1,inf)

rele =

     5.830000000000002e-04

k=4488

k =

        4488

k*relr

ans =

   0.00203999999968

relr/k

ans =

     1.012801814782570e-10

diary off