iter      chisq       delta/lim  lambda   a             b            
   0 1.4700000000e+02   0.00e+00  1.40e+01    1.000000e+00   1.000000e+00
   1 1.6935544886e+01  -7.68e+05  1.40e+00    7.830590e-01   9.780369e-01
   2 1.3496165132e+01  -2.55e+04  1.40e-01    6.629727e-01   1.501074e+00
   3 1.3285717162e+01  -1.58e+03  1.40e-02    6.251403e-01   1.695706e+00
   4 1.3285714286e+01  -2.16e-02  1.40e-03    6.250000e-01   1.696429e+00
iter      chisq       delta/lim  lambda   a             b            

After 4 iterations the fit converged.
final sum of squares of residuals : 13.2857
rel. change during last iteration : -2.16481e-07

degrees of freedom    (FIT_NDF)                        : 4
rms of residuals      (FIT_STDFIT) = sqrt(WSSR/ndf)    : 1.82248
variance of residuals (reduced chisquare) = WSSR/ndf   : 3.32143

Final set of parameters            Asymptotic Standard Error
=======================            ==========================
a               = 0.625            +/- 0.1552       (24.84%)
b               = 1.69643          +/- 0.7761       (45.75%)

correlation matrix of the fit parameters:
                a      b      
a               1.000 
b              -0.969  1.000