## 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.  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 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