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 compatible
           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.

      -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 geodetic 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 incompatible -R
      and -I arguments.  To reset the x- and y-increments we run

      grdedit junk.grd -A

SEE ALSO

      gmt, grd2xyz, xyz2grd