Important note: Covariance errors (2014.10.30)
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Applies to: LOCSEARCH MET and LOCSEARCH OCT
The algorithm for calculating the covariance of the PDF scatter sample used in NLLoc
was subject to precision errors when the expectation of the scatter sample (e.g. the event location)
was far from the origin of the NLL coordinates system relative to the extent of the PDF scatter sample.
Several tests indicate that "Far from the origin" is of the order of 1000 times the extent of the PDF scatter sample.

Errors in covariance will affect the ellipsoid and ellipse, standard-errors (erh, erz, etc.).

For teleseismic locations (NLL GLOBAL mode) errors with the old algorithm occur primarily in
longitude (X), increasing with expectation longitude and occasionally becoming large towards longitude +/-180deg.
For local studies in rectangular coordinates where the NLL coordinates origin is far from the network
and target sources, the errors may be large.  This may be the case, for example, for a micro-seismic study
using a regional, metric-based cartesian grid coordinate system with origin far from the study area.
For local studies in rectangular coordinates where the NLL coordinates origin is within or near the network
and target sources, the errors should be very small or negligible.

The algorithm for calculating the covariance of the PDF scatter sample used in NLLoc v.6.03.00 and later does not
have these precision errors and is valid for locations far from the origin of the coordinate system.


Complete NonLinLoc distribution software package
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	Unpack source files: unpack: NLL[VER]_src.tgz
	Set bin path:
	export MYBIN=<path>/bin
	To build:
	cd src
	OSX, Solaris:
		make all
	Linux:
		make -R all
	See http://alomax.net/nlloc and http://alomax.net/nlloc -> tutorials for further information


NLLoc_func_test program demonstrating running NLLoc through a function call
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	Unpack source files: unpack: NLL[VER]_src.tgz
	Set bin path:
		export MYBIN=<path>/bin
	To build:
		cd src
	In Makefile, uncomment the line:
	GNU_SOURCE=-D _GNU_SOURCE
	and comment the line:
	GNU_SOURCE=
	To build:
	OSX, Solaris (not tested):
		make NLLoc_func_test_
	Linux:
		make -R NLLoc_func_test_
		cd ..
	Unpack demo files: unpack: NLL[VER]_func.tgz
	To run:
		cd nll_func
		./run_func.sh
	To clean
		rm -rf out/*
		cd ..
	See nll_func/run_func.sh for more detail.


ttime_func_test program demonstrating reading values from 2D or 3D grid file through a function call
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	Unpack source files: unpack: NLL[VER]_src.tgz
	Set bin path:
		export MYBIN=<path>/bin
	To build:
	cd src
	To build:
	OSX, Solaris (not tested):
		make ttime_func_test
	Linux:
		make -R ttime_func_test
		cd ..
	Unpack demo files: unpack: NLL[VER]_func.tgz
	To run:
		cd ttime_func
		./run_func.sh
		cd ..
	See ttime_func/run_func.sh for more detail.
