This function solves a USL model using non linear regression with least
squares. It uses the function nls
with the "port
"
algorithm to perform the calculation. All restrictions of the algorithm
apply.
usl.solve.nls(model)
A data frame with two columns containing the values of the predictor variable in the first column and the values of the response variable in the second column.
A list containing three elements: the scale.factor of the model, the model coefficients sigma and kappa.