Dear R-helpers:
I have a data set (over 21,000 records) which fitted to a nonlinear
function with 5 parameters using nls() without problems. However, when I
fitted it to the same function using glns(), an error occurred:
Error in gnls(h2 ~ SiAB(b0, b1, b2, b3, b4, b5, h1, t1, t2), data lfdnlp1, :
Step halving factor reduced below minimum in NLS step
The following is the printout of the gnls() with verbose = T :
NLS step: RSS = 60051.74
model parameters:0.0142528 -0.40339 1.07913 0.708258 -0.35343 0.333127
iterations: 7
Convergence:
params
1.083799
NLS step: RSS = 60051.73
model parameters:0.0142575 -0.403859 1.07918 0.708292 -0.353546
0.333152
iterations: 7
Convergence:
params
0.001160867
Error in gnls(h2 ~ SiAB(b0, b1, b2, b3, b4, b5, h1, t1, t2), data = lfdnlp1,
:
Step halving factor reduced below minimum in NLS step
I changed the nlsTol to 1e-5 (default is 1e-3) without help. Any suggestions
or workaround for the error? I am using R 1.50 on W2K.
TIA,
Richard
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