<< Click to Display Table of Contents >> Navigation:  »No topics above this level« Linear analysis

In this section we look at various kinds of linear analysis that can be undertaken as an adjunct to model calibration. Most of these analyses require a PEST-calculated Jacobian matrix. So important is this matrix that the PEST suite provides tools that do nothing else but provide access to parts of it, and support its manipulation. We begin this section by looking at these tools.

PEST updates the Jacobian matrix during every iteration of the inversion process. It is stored in binary compressed form in a file named case.jco where case is the filename base of the PEST control file. This is often referred to as a "JCO file". Before undertaking post-calibration linear uncertainty analysis, it is sometimes best to re-compute this matrix using optimised parameters. This can be done as follows:

1.Use the PARREP utility to create a PEST control file in which initial parameter values are optimised parameter values.

2.Set the NOPTMAX control variable in this file to -1 or -2.

3.Run PEST, BEOPEST or PEST_HP. These programs will cease execution as soon as they have filled the Jacobian matrix.

Note that the Jacobian matrix does not contain weighted sensitivities. Its elements are independent of the weights assigned to observations in a PEST control file.