NONLINEM38, MATLAB code for a nonlinear model of the EM-38

This directory contains a MATLAB implementation of a method for prediction of EM-38 readings from a layered earth conductivity model and the inversion of a layered conductivity model from above ground EM-38 measurements.

Note that the code is written to work with the "quadrature" component data. The instrument can also be set to provide an "in-phase" reading, but that isn't implemented here (although it would be a relatively small change.) The code could also be modified to work with other ground conductivity meters, but parameters such as the coil spacing and operating frequency would have to be adjusted.

This code was originally written in Fortran for the paper:

J. M. H. Hendrickx, B. Borchers, D. L. Corwin, S. M. Lesch, A. C. Hilgendorf and J. Schlue. Inversion of Soil Conductivity Profiles from Electromagnetic Induction Measurements: Theory and Experimental Verification. Soil Science Society of America Journal. 66(3):673--685, 2002.

The original Fortran code made use of routines from the IMSL library that are no longer available- it is hoped that this version will be useful to researchers. In order to make any sense of this code you will need to have a copy of the above paper.

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