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This program is part of a Helmert blocking adjustment system for GPS parameters including site coordinates, orbit parameters, earth orientation and troposphere parameters. In the Helmert blocking system the program Pages processes all observational data. It generates observation equations and subsequently normal equations which are forward reduced to eliminate the nuisance parameters, primarily clock errors and bias unknowns. This produces a normal equation matrix which is passed forward to be combined with other initial data sets into a global adjustment by the program Gpscom. In addition to the nuisance parameters which are eliminated the program Pages seperates the other unknowns into "local" unknowns, which means they have no observations connecting them to any local unknowns in any other initial data set, and "global" unknowns which are parameters that, in most cases, will be included in observations present in some other initial data set. Both the local and the global unknowns are saved in a normal equation file which is passed forward to the program Gpscom to determine the solution and inverse for the global parameters which are then saved in an inverse file. The function of the program Llsolv is to read the global inverse file and then sequentially read each initial normal equation file substitute the global inverse elements and solution vector into the initial normal equation file and propagate the solution and inverse to include the local unknowns. The result of the Llsolve step is a print file of the local solution vector and a new set of inverse files for each initial data set.
This program will read a file "llsolv.inp" containing the name of a "higher level" inverse file and a list of file names of GPS "lower level" normal equation files. These normal equation files will then have the elements of the normal equations for the "global" parameters replaced with those from the inverse of the higher level system and the remaining lower level terms will be back solved and their inverse terms computed. This will provide results for the local parameters which are rigidly correct values for a combined global adjustment of all data sets.
This program was written in FORTRAN. Predominantly ANSI standard FORTRAN, a few isolated routines query the operating system for time and date, user and system identification. These "system" routines are inherently non-portable but, should be easily modified or disabled.
The input data for this program is a list of file names, the higher level inverse normal equation file containing the results of a combined adjustment computed by program Gpscom, and the lower level normal equation files for which the final adjusted parameters and inverse elements are to be computed. An input file with the name llsolv.inp is required to be in the working directory in which the program llsolv is executed. The file llsolv.inp must contain in the following order the specified data.
Line 1) Global path name for the directory where the output file is to be placed. Include a trailing /.
Line 2) Combined higher level inverse file name.
Line 3) Contains the keywork "DATASETS" begining in column 1.
Line 4-n) List of input normal equation files into which the global solution contained in the higher level inverse file is to be propagated.
Line n+1) Contains the keywork "END_DF " including two trailing blanks begining in column 1.
Example
/proc/gl/work/logs_igs/weekly_igs/
/proc/gl/work/logs_igs/weekly_igs/Wk1011/ngs10117.nrm.inv
DATASETS
/proc/gl/work/logs_igs/99.143/nrm.143
/proc/gl/work/logs_igs/99.144/nrm.144
/proc/gl/work/logs_igs/99.145/nrm.145
/proc/gl/work/logs_igs/99.146/nrm.146
/proc/gl/work/logs_igs/99.147/nrm.147
/proc/gl/work/logs_igs/99.148/nrm.148
/proc/gl/work/logs_igs/99.149/nrm.149
END-DF
c C OUTPUT : C ------------------ C c 1) a file of the inverse terms of the normal equations c c 2) A text file of solution results. c c 3) a Sinex file of solution results. c
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