Regression modeling of ground-water flow; Supplement 1 : modifications to the computer code for nonlinear regression solution of steady-state ground-water flow problems

Modifications to the computer code for nonlinear regression solution of steady-state ground-water flow problems in "Regression Modeling of Ground-Water Flow", by R.L. Cooley and R.L. Naff (U.S. Geological Survey, Techniques of Water Resources Investigations, book 3, chap. B4, 1990), improve the performance of the code. The changes 1) allow any model parameters to be transformed to natural logarithms, and 2) improve the procedure for computing the parameter that damps changes in the values of model parameters for each iteration of the solution method. In addition, the user is shown how to read prior information separately from the initial set of parameter values.