Zero variance matrix components reported by adjust.exe when --report-results is run on phased-staged networks

[nicgowans]

Description

Zero variance matrix components are reported by adjust.exe in --report-results mode when a phased-staged adjustment is run. The effects are seen in:

• *.apu (zero variance matrix components, error ellipses, and -nan(ind) Hz PosU values)
• *.xyz (zero adjusted standard deviations for stations)
• *.adj (zero adjusted standard deviations for stations and measurements, and associated flow on into nstats, rigorous sigma zero, chi squared and pelzer)

Adjustments run in simultaneous or phased-multi modes are not affected.

DynAdjust version info

• Version: 1.2.7, Release (64-bit)
• Build: Mar 29 2023, 10:01:09 (MSVC++ 1935)

Steps to reproduce
To reproduce:

1. Run a network adjustment in phased-staged mode
2. Reproduce the adjustment results with adjust.exe using the following commands:

adjust.exe -n network_name --report-results --phased --staged --create-stage-files --purge-stage-files [etc]

3. Review *.apu, *.adj, *.xyz

Station                     Latitude      Longitude    Hz PosU    Vt PosU   Semi-major   Semi-minor  Orientation        Variance(X)        Variance(Y)        Variance(Z)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(1127a)_300559         -33.595529013  150.595927204  -nan(ind)     0.0000       0.0000       0.0000       0.0000    0.000000000e+00    0.000000000e+00    0.000000000e+00
                                                                                                                                       0.000000000e+00    0.000000000e+00
                                                                                                                                                          0.000000000e+00  

Expected behaviour
Variance matrix and associated uncertainties/statistics re-produced as per simultaneous and phased-multi modes

Station                     Latitude      Longitude    Hz PosU    Vt PosU   Semi-major   Semi-minor  Orientation        Variance(X)        Variance(Y)        Variance(Z)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------
(1127a)_300559         -33.595529013  150.595927204     0.0214     1.9408       0.0092       0.0083     118.1119    5.155713583e-01   -2.857467958e-01    3.975374830e-01
                                                                                                                                       1.584764161e-01   -2.203539908e-01
                                                                                                                                                          4.066365232e-01 

Screenshots
*.apu file:

*.adj file:

*.xyz file:

Operating system

• Windows 10

[nicgowans]

Thanks for your recent efforts to review this issue, @rogerfraser.

To summarise our email exchange, the above behaviour is the result of the combined use of --report-results and --create-stage-files which re-creates the empty stage files containing the a-posteriori measurement/station variances matrices (initialised as zero) and then reports the zero results from the newly initialised and unpopulated stage files.

Therefore, the action required to prevent the above result is to modify adjust such that it will:

• refuse to proceed when both --report-results and --create-stage-files options are provided; and
• return a warning to screen.

[rogerfraser]

Many thanks @nicgowans for confirming the behaviour of the issue, and for suggesting a fix to prevent adjust from inadvertently producing incorrect results. A fix to trap the combined use of --report-results and --create-stage-files has been implemented and will appear in the 1.2.8 release.