Errata

Chapter 8

Page 228: Minor changes in fitted variogram values following the change to BLAS/LAPACK from Meschach linear algebra functions in gstat 1.1-0. Page 236: Following the change to BLAS/LAPACK from Meschach linear algebra functions in gstat 1.1-0, the poor matrix condition check example in chunk 61 should be omitted. The Choleski decomposition used from gstat 1.1-0 on indicates that the resulting covariance matrix is not positive definite, and generates missing values. Page 241: Minor change in prediction variance values following the change to BLAS/LAPACK from Meschach linear algebra functions in gstat 1.1-0. Pages 241-242: df constructed wrongly; "it would appear as though the estimate of the intercept is -2.47 and the estimate of beta1 is 6.95. I wonder if these labels are switched, as a simple lm of log(zinc) on sqrt(dist) has intercept 6.99 and slope -2.54 - there is a negative relationship of log zinc with sqrt(dist)"; thanks to Susan Service. Script updated 30 August 2017. Page 244: Minor change in prediction variance values following the change to BLAS/LAPACK from Meschach linear algebra functions in gstat 1.1-0. Pages 244-245, section 8.5.10, chunk 85: Starting with gstat 1.1-0, the option to set cn_max is no longer needed (nor present from 1.1-1), due to the replacement of the meschach matrix library with the Lapack/BLAS library. The new behaviour in case of non-positive definiteness is printing of the warning (Covariance matrix singular at location [x,y,z]: skipping...) and continuing with the next location. Singularity is now by default detected by the Lapack routine dpotrs, which uses Choleski decomposition and breaks on non-positive definiteness. Gstat versions prior to 1.1-0 used the LDL' decomposition instead of the Choleski decomposition. Some non-positive definite matrices can be decomposed by LDL', but not by Choleski. Compatibility with the pre-gstat 1.1-0 behaviour is obtained when the variable choleski is set to the value 0, in the same way cn_max was defined. Page 245: Minor change in prediction variance values following the change to BLAS/LAPACK from Meschach linear algebra functions in gstat 1.1-0.