NAME

       x2sys_solve - Determine systematic corrections from crossovers

SYNOPSIS

       x2sys_solve   -Ccolumn   -TTAG   -Emode  [  COE_list.d  ]  [  -V  ]  [  -W  ]  [  -Z  ]  [
       -bi[s|S|d|D[ncol]|c[var1/...]] ]

DESCRIPTION

       x2sys_solve  will  use  the  supplied  crossover  information  to  solve  for   systematic
       corrections that can then be applied per track to improve data quality. Several systematic
       corrections can be solved for using a least-squares approach.  Note: Only one data  column
       can be processed at the time.

       -T     Specify the x2sys TAG which tracks the attributes of this data type.

       -C     Specify which data column you want to process.  Needed for proper formatting of the
              output correction table and must match the same  option  used  in  x2sys_list  when
              preparing the input data.

       -E     The  correction type you wish to model.  Choose among the following functions f(p),
              where p are the m parameters per track that we  will  fit  simultaneously  using  a
              least squares approach:
              c will fit f(p) = a (a constant offset); records must contain cruise ID1, ID2, COE.
              d  will  fit  f(p)  =  a + b * d (linear drift; d is distance; records must contain
              cruise ID1, ID2, d1, d2, COE.
              g will fit f(p) = a + b sin(y)^2   (1980-1930  gravity  correction);  records  must
              contain cruise ID1, ID2, latitude y, COE.
              h will fit f(p) = a + b cos(H) + c cos(2H) + d sin(H) + e sin(2H) (magnetic heading
              correction); records must contain cruise ID1, ID2, heading H, COE.
              s will fit f(p) = a * z (a unit scale correction); records must contain cruise ID1,
              ID2, z1, z2.
              t  will  fit  f(p)  =  a  + b * (t - t0) (linear drift; t0 is the start time of the
              track); records must contain cruise ID1, ID2, t1-t0, t2-t0, COE.

OPTIONS

       No space between the option flag and the associated arguments.

       COE_list.d
              Name of file with the required crossover columns as produced by x2sys_list.   NOTE:
              If  -bi  is  used then the first two columns are expected to hold the integer track
              IDs; otherwise we expect those columns to hold the text string  names  of  the  two
              tracks.

       -V     Selects  verbose  mode,  which  will  send progress reports to stderr [Default runs
              "silently"].

       -W     Means that each input records has an extra column with  the  composite  weight  for
              each  crossover record.  These are used to obtain a weighted least squares solution
              [no weights].

       -Z     For -Ed and -Et, determine the earliest time or shortest distance for  each  track,
              then  use  these  values  as  the  local  origin  for  time  duration  or  distance
              calculations.  The local origin is then included in the correction  table  [Default
              uses 0].

       -bi    Selects  binary  input.   Append  s  for  single precision [Default is d (double)].
              Uppercase S or D will force byte-swapping.  Optionally, append ncol, the number  of
              columns  in your binary input file if it exceeds the columns needed by the program.
              Or append c if the input  file  is  netCDF.  Optionally,  append  var1/var2/...  to
              specify the variables to be read.

EXAMPLES

       To fit a simple bias offset to faa for all tracks under the MGD77 tag, try

       x2sys_list COE_data.txt -V -T MGD77 -C faa -F nc  > faa_coe.txt
       x2sys_solve faa_coe.txt -V -T MGD77 -C faa -E c > coe_table.txt

       To fit a faa linear drift with time instead, try

       x2sys_list COE_data.txt -V -T MGD77 -C faa -F nTc  > faa_coe.txt
       x2sys_solve faa_coe.txt -V -T MGD77 -C faa -E t > coe_table.txt

       To estimate heading corrections based on magnetic crossovers associated with the tag MGD77
       from the file COE_data.txt, try

       x2sys_list COE_data.txt -V -T MGD77 -C mag -F nhc > mag_coe.txt
       x2sys_solve mag_coe.txt -V -T MGD77 -C mag -E h > coe_table.txt

       To estimate unit scale corrections based on bathymetry crossovers, try

       x2sys_list COE_data.txt -V -T MGD77 -C depth -F nz > depth_coe.txt
       x2sys_solve depth_coe.txt -V -T MGD77 -C depth -E s > coe_table.txt

SEE ALSO

       x2sys_binlist(1),   x2sys_cross(1),   x2sys_datalist(1),   x2sys_get(1),    x2sys_init(1),
       x2sys_list(1), x2sys_put(1), x2sys_report(1)