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.
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
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
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.