NAME

      sample1d - Resampling of 1-D data sets

SYNOPSIS

      sample1d infile [ -Fl|a|c ] [ -H[nrec] ] [ -Ixinc ] [ -M[flag] ] [
      -Nknotfile ] [ -Sxstart ] [ -Tx-col] [ -bi[s][n] ] [ -bo[s] ]

DESCRIPTION

      sample1d reads a multi-column ASCII [or binary] data set from file [or
      standard input] and resamples the timeseries/profile at locations
      where the user needs the values.  The user must provide the column
      number of the independent (monotonically increasing or decreasing)
      variable.  Equidistant or arbitrary sampling can be selected.  All
      columns are resampled based on the new sampling interval.  Several
      interpolation schemes are available.

      infile
           This is a multi-column ASCII [of binary, see -b] file with one
           column containing the independent variable (which must be
           monotonically in/de-creasing) and the remaining columns holding
           misc. data values.  If no file is provided, sample1d reads from
           standard input.

OPTIONS

      No space between the option flag and the associated arguments.

      -F   Choose from l (Linear), a (Akima spline), and c (natural cubic
           spline) [Default is -Fa].  You may change the default
           interpolant; see INTERPOLANT in your .gmtdefaults file.

      -H   Input file(s) has Header record(s).  Number of header records can
           be changed by editing your .gmtdefaults file.  If used, GMT
           default is 1 header record.

      -I   xinc defines the sampling interval. [Default is the separation
           between the first and second abcissa point in the infile]

      -M   Multiple segment file.  Segments are separated by a record whose
           first character is flag.  [Default is '>'].

      -N   knotfile is an optional ASCII file with the x locations where the
           data set will be resampled in the first column

      -S   For equidistant sampling, xstart indicates the location of the
           first output value. [Default is the smallest even multiple of
           xinc inside the range of infile]

      -T   Sets the column number of the independent variable [Default is 0
           (first)].


      -bi  Selects binary input.  Append s for single precision [Default is
           double].  Append n for the number of columns in the binary
           file(s).  [Default is 2 (or at least the number of columns
           implied by -T].

      -bo  Selects binary output.  Append s for single precision [Default is
           double].

EXAMPLES

      To resample the file profiles.tdgmb, which contains
      (time,distance,gravity,magnetics,bathymetry) records, at 1km
      equidistant intervals using Akima's spline, try

      sample1d profiles.tdgmb -I1 -Fa -T1 > profiles_equi_d.tdgmb

      To resample the file depths.dt at positions listed in the file
      grav_pos.dg, using a cubic spline for the interpolation, try

      sample1d depths.dt -Ngrav_pos.dg -Fc > new_depths.dt

SEE ALSO

      gmt, filter1d