ELIM/MILE                                                  ELIM  Ver. 2007.07.18

       Procedure for automatic outliers elimination/restoration

       Description of menu items.
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(H) -- Put on-line help on the screen, which you are reading just now.

(A) -- Set acceleration factor ( greater than 0 ). This option allows to speed
       up the process of elimination/restoration by the expense of some 
       worsening performance: residuals are updated after N operations of
       elimination/restoration, where N is the acceleration factor. Best choice
       is N=1, but it may lead to too slow work for session with tens of
       thousands observations. Increasing acceleration factors decreases 
       computation time approximately by N times, but it may lead not the 
       optimal choice of the outlier/candidate_in_restoration. It is not
       recommended to use acceleration factor more than 1 unless computational
       expenses appear really intolerable.

(X) -- Set upper limit for formal uncertainty. Observations with formal 
       uncertainty (full sigma: correlator supplied and reweight) exceeding
       the limit will be marked as outliers in ELIM mode and will not be 
       considered eligible for restoration in MILE mode. If the limit is set 
       to zero then this criteria will not be taken into account.

(E) -- EQM speed-up. Toggles flag of whether to save equations of conditions 
       in memory. Saving equations of conditions in memory speeds up 
       computation considerably. However, it may appear that it is not enough 
       operating memory to keep all equations of conditions. Then this flag 
       should be lifted. EQM speed-up flag can be reset only before processing 
       the first observation.

(U) -- Set upper threshold (in psec) for detection of outlier. Each observation
       will be passed through two tests: threshold test and n-sigmas cutoff 
       test. If (unweighted) residual of the observation used in solution 
       exceeds in modulo the absolute value of the specified threshold,
        this observation is marked as outlier in ELIM mode. If (unweighted) 
       residual of not used in solution but recoverable observation is less 
       in modulo than the absolute value of the specified threshold then this 
       observation is marked as a candidate to restoration in MILE mode. 
       If the value of threshold is set up to zero, then threshold criterion 
       will not be used. The threshold criteria may be negative. The sign of
       the threshold criteria is used when both the threshold and cutoff 
       criteria are used (see below).

(C) -- Set upper level of cutoff limit for detection of outlier using n-sigma
       criterion. Each observation is passed through two tests: threshold 
       test and n-sigmas cutoff test. If normalized residual of the observation 
       used in solution exceeds in module the specified cutoff limit then this 
       observation is marked as outlier in ELIM mode. If normalized 
       residual of the recoverable but not used in solution observation is less
       in module than the specified cutoff limit then this observation is
       marked as a candidate to restoration in MILE mode. If the value of 
       cutoff is set up as zero then n-sigmas cutoff criterion will not be 
       used. 

       If both the threshold and n-sigma criteria are used in ELIM mode 
       and the threshold is positive, then an observation is considered as
       a candidate for outlier if its residual EITHER greater than the 
       threshold OR its normalized residual greater than the cutoff criteria.
       The observation with the maximal in modulo normalized residual among 
       those which satisfy either criterion is marked as the best candidate
       for elimination.

       If both the threshold and n-sigma criteria are used in ELIM mode 
       and the threshold is negative then an observation is considered as
       a candidate for outlier if its residual greater than the absolute 
       value of the threshold AND its normalized residual is greater than 
       the cutoff criteria. The observation with the maximal in modulo 
       normalized residual among those which satisfy both criteria is 
       marked as the best candidate for elimination.

       If both the threshold and n-sigma criteria are used in MILE mode and
       the threshold is positive, then an observation is considered as
       a candidate for restoration if its residual is EITHER less than the 
       threshold OR its normalized residual is less than the cutoff criteria.
       The observation with the minimal in modulo normalized residuals among 
       those which satisfy either criterion is marked as the best candidate 
       for restoration.

       If both the threshold and n-sigma criteria are used in MILE mode and
       the threshold is negative, then an observation is considered as
       a candidate for restoration if its residual is less than the 
       absolute value of the threshold AND its normalized residual is less 
       than the cutoff criteria. The observation with minimal in modulo 
       normalized residuals among those which satisfy both criteria is 
       marked as the best candidate for restoration.

(Y) -- Normalization of "normalized postfit residuals" may be done in two 
       modes: 'global' mode when dispersion of postfit residuals used for 
       normalization is calculated for all used observations of the database 
       or in 'baseline' mode when this dispersion is calculated for used 
       observations made at the same baseline as the considered observation.
     
(Q) -- Quality code limit sets the minimal quality code acceptable for the 
       observation considered as candidate in restoration. All observations
       with quality code less than specified limit are considered as 
       unrecoverable ones and cannot be restored by MILE. Quality code limit 
       may have values in the range [1, 9].
       
(D) -- Statistics of the solution is not calculated automatically when ELIM is
       called. Entering D you can initialize ELIM/MILE and update statistics
       of the solution.
       
(M) -- Try to resolve ambiguity. If YES then MILE tries to resolve ambiguities
       on the fly. It checks whether the observation is a good candidate for
       restoration after getting rid from the ambiguities. If the observation
       with ambiguities is the best candidate for restoration them MILE 
       restores it, changes ambiguities of this observation and possibly 
       changes ambiguities of others suppressed observations of the same scan
       in order to keep misclosure. MILE will not restore observation if the
       change of ambiguities with conservation of misclosure would require 
       changes of ambiguities of used observations.
      
(I) -- Ionosphere for ambiguities. Forces MILE to uses effective ionosphere
       free ambiguities spacing when it tries to resolve ambiguities on the 
       fly. Should be always used when the option (M) is YES except some
       specific cases.

(R) -- Refresh the screen.

(-) -- Change singularity check (ref. documentation for SET_SNGCHK). 
       Singularity check action REPARAMETERIZE is recommended to be used 
       in order to avoid abnormal termination caused by normal matrix 
       singularity which may give rise due to elimination too many 
       observations.

(') -- Change suppression method. Codes of supported suppression methods will 
       be displayed and used may select appropriate suppression method. 
       Suppression method influence on the status of observations and on 
       possibility to suppress them.

(V) -- Verbosity level. Two values are allowed: 0 what means silent mode or
       1 -- verbose mode. Some messages will appear at the screen in verbose
       mode indicating the current work of the program. Only error message will
       printed out in silent mode.

(N) -- Toggle confirmation mode. Confirmation will be inquired before each 
       operation elimination or restoration in confirmation mode. User can 
       reply Y, N, A, S in a response. "Y" means yes, "N" means no, "A" means 
       yes and not to ask further confirmation, "S" means to stop further 
       elimination or restoration and coming to the main menu ELIM. Switching 
       confirmation mode "on" sets automatically verbosity level to 1.

(S) -- Save results of the work (to rewrite them from temporary data 
       structures to scratch file), show the listing of parameter estimation by
       calling CRES and to return to OPTIN.

(O) -- Return to OPTIN without saving results.

(P) -- Start doing outliers elimination or restoration.

(T) -- Toggle mode between ELIM (outliers elimination) and MILE (restoration 
       of suppressed observations).

(W) -- Call utility UPWEI (ref. documentation for UPWEI) for updating weights.
       Additive baseline-dependent (or baseline-independent) corrections to 
       the weights will be found using iterative procedure. After having 
       quadratically added to the a priori weights the ratio of the chi-square 
       to its mathematical expectation become near to unity.
