fields tests {fields}R Documentation

Testing fields functions


Some of the basic methods in feilds can be tested by directly implementing the linear algebra using matrix expressions. These comparisons are done in the the R source code test files in the tests subdirectory of fields. The function is useful for comparing the tests in a meaninful and documented way.

Usage xtest,xtrue,  tol= 1.0e-8, relative=TRUE, tag=NULL)


xtest Vector of target values
xtrue Vector of reference values
tol Tolerance to judge whether the test passes.
relative If true a relative error comparison is used. (See details below.)
tag A text string to be printed out with the test results as a reference


The scripts in the tests subdirectory are

Tests basic parts of the Krig and Tps functions including replicated and weighted observations.
Tests computations of standard errors for the Kriging estimate.
Tests approximate standard errors for the Krig function found by Monte Carlo conditional simulation.

Tests predictions and A matrix when an off diagonal observation weight matrix is used.
Tests standard errors when an off diagonal observation weight matrix is used.

To run the tests just attach the fields library and source the testing file. In the the fields source code these are in a subdirectory "tests". is used to print out the result for each individual comparison. Failed tests are potentially very bad and are reported with a string beginning

"FAILED test value = ... "

If the object exists ( it can have any value), all the tests that pass print text beginning,

" PASSED test at tolerance ..."

This startegy means that if all tests succeed nothing and the object does not exist then nothing is printed in the test scripts. This is option simplifies the output scripts for running through the tests – no news is good news.

FORM OF COMPARISON: The actual test done is the sum of absolute differnces:

test value = sum( abs(c(xtest) - c( xtrue) ) ) /denom

Where demon is either mean( abs(c(xtrue))) for relative error or 1.0 otherwise.

Note the use of "c" here to stack any structure in xtest and xtrue into a vector.

[Package fields version 3.3.1 Index]