NAME

     grdedit - Modifying the header in a 2-D grdfile


SYNOPSIS

     grdedit        grdfile        [        -A        ]         [
     -Dxunit/yunit/zunit/scale/offset/title/remark       ]      [
     -Rwest/east/south/north[r] ] [ -S ]


DESCRIPTION

     grdedit reads the header information in a binary 2-D grdfile
     and  replaces  the  information  with values provided on the
     command line [if any].  As an option,  global,  geographical
     grids  (with  360 degrees longitude range) can be rotated in
     the east-west direction.  grdedit  only  operates  on  files
     containing a grdheader.
          No space between the option  flag  and  the  associated
     arguments.   Use  upper  case for the option flags and lower
     case for modifiers.

     grdfile
          Name of the 2-D grdfile to modify



OPTIONS

     -A   If necessary, adjust the file's x_inc, y_inc to be com-
          patible  with its domain (or a new domain set with -R).
          Older gridfiles (i.e., created prior to GMT 3.1)  often
          had excessive slop in x_inc, y_inc and an adjustment is
          necessary.  Newer files are created correctly.

     -D   Give new values for xunit, yunit, zunit, scale, offset,
          title,  and  remark.   To  leave  some  of  the  values
          untouched, specify = as the new value.

     -R   west, east, south, and  north  specify  the  Region  of
          interest.  To specify boundaries in degrees and minutes
          [and seconds], use the dd:mm[:ss] format.  Append r  if
          lower  left  and  upper right map coordinates are given
          instead of wesn.  The new w/e/s/n values  will  replace
          those  in  the  grid,  and  the x_inc, y_inc values are
          adjusted, if necessary.

     -S   For global, geographical grids only.  Grid values  will
          be shifted laterally according to the new borders given
          in -R.


EXAMPLES

     Let  us  assume  the   file   data.grd   covers   the   area
     300/310/10/30.   We  want to change the boundaries from geo-
     detic longitudes to geographic and put a new  title  in  the
     header.  We accomplish this by

     grdedit   data.grd   -R-60/-50/10/30    -D=/=/=/=/=/"Gravity
     Anomalies"/=

     The grid world.grd has the limits  0/360/-72/72.   To  shift
     the data so that the limits would be -180/180/-72/72, use

     grdedit world.grd -R-180/180/-72/72 -S

     The file junk.grd was created prior to GMT 3.1 with incompa-
     tible -R and -I arguments.  To reset the x- and y-increments
     we run

     grdedit junk.grd -A


SEE ALSO

     gmt(l), grd2xyz(l), xyz2grd(l)