x = 1:10;
y = [6.2 9.5 12.3 13.9 14.6 13.5 13.3 12.7 12.4 11.9];
A = [ones(10,1) x']

A =

     1     1
     1     2
     1     3
     1     4
     1     5
     1     6
     1     7
     1     8
     1     9
     1    10

c = A\(log(y)-log(x))'

c =

   1.96319223063350
  -0.18384897401197

f = inline('exp(1.96319223063350)*x.*exp(-0.18384897401197*x)-4')

f =

     Inline function:
     f(x) = exp(1.96319223063350)*x.*exp(-0.18384897401197*x)-4

fzero(f,0)

ans =

   0.63068619092697

fzero(f,20)

ans =

  19.21447694093067

diary off