NAME
     EXT - NMRPipe Extract Region

SYNOPSIS
     nmrPipe -fn EXT [-time | -left | -right | -mid]  [-round  n]
     [-pow2]  [-sw]  [-x1  xFirst]  [-xn xLast] [-y1 yFirst] [-yn
     yLast]

DESCRIPTION
     EXT extracts a selected region of the given data. The  loca-
     tion  of the region can be specified in units of points, Hz,
     PPM or percent, or in generalized terms such as left half or
     right  half.   Generally,  only  an  extract  region for the
     X-Axis will be specified, but options are available for lim-
     iting  the region coordinates in the Y-Axis is well.  If the
     -sw flag is used, PPM calibration and other header  informa-
     tion  will  be  updated automatically to reflect the coordi-
     nates of the extracted region.

OPTIONS
     -left
          This flag will set the extract region so that the  left
          half of the data will be retained.  The right half will
          be discarded, reducing the data size  by  a  factor  of
          two.

     -right
          This flag will set the extract region so that the right
          half  of the data will be retained.  The left half will
          be discarded, reducing the data size  by  a  factor  of
          two.

     -mid This flag will set the extract region so that the  cen-
          tral  50%  of  the data will be retained.  The left and
          right quarters will be  discarded,  reducing  the  data
          size by a factor of two.

     -time
          When used on time-domain data, this  flag  will  reduce
          the  data  size  to  the valid complex time-domain size
          recorded in the header.  It is commonly used to  remove
          padding added by the spectrometer (see EXAMPLES below).

     -round N
          This flag will  increase  the  size  of  the  extracted
          region  so  that  it  is  a multiple of N.  The default
          value is 1, which means no adjustment will be made.

     -pow2
          This option will increase the  size  of  the  extracted
          region so that it is a power of two.

     -sw  When the -sw flag is used on frequency-domain data,  it
          will  update  the  sweep width and other chemical shift
          calibration information to accommodate the new range of
          the  extracted  data  region.   It will also adjust the
          recorded number of valid-time domain points, to reflect
          the  number  of  points which would be available if the
          extracted region was inverse transformed.

          When the -sw flag is used on time-domain data, it  will
          adjust  the  recorded  time-domain  size to reflect the
          size of the extracted region.

     -x1 xFirst
          Specifies the X-Axis location of the first point of the
          region  to  extract.  By default, this is point 1.  The
          point location can  be  specified  with  no  units  for
          points, or with units Hz, PPM, or %.  When specifying a
          location with a unit label, there should be  no  spaces
          between the numerical value and the unit label.

     -xn xLast
          Specifies the X-Axis location of the last point of  the
          region  to extract.  By default, this is the last point
          in the X-Axis.  The point  location  can  be  specified
          with  no units for points, or with units Hz, PPM, or %.
          When specifying a location with  a  unit  label,  there
          should be no spaces between the numerical value and the
          unit label.

     -y1 yFirst
          Specifies the Y-Axis location of the first point of the
          region  to  extract.  By default, this is point 1.  The
          point location can  be  specified  with  no  units  for
          points, or with units Hz, PPM, or %.  When specifying a
          location with a unit label, there should be  no  spaces
          between  the  numerical value and the unit label.  Note
          that for hypercomplex data,  a  Y-Axis  point  location
          should  be  specified  in  terms of interleaved points,
          rather than complex points.

     -yn yLast
          Specifies the Y-Axis location of the last point of  the
          region  to extract.  By default, this is the last point
          in the Y-Axis.  The point  location  can  be  specified
          with  no units for points, or with units Hz, PPM, or %.
          When specifying a location with  a  unit  label,  there
          should be no spaces between the numerical value and the
          unit label.  Note that for hypercomplex data, a  Y-Axis
          point  location  should be specified in terms of inter-
          leaved points, rather than complex points.


EXAMPLES
     Extract the left half of the spectrum, update the PPM  cali-
     bration and other header information accordingly:


        nmrPipe -fn EXT -left -sw


     Extract the range of data from 10.5  PPM  to  6.2  PPM,  and
     update  the  PPM  calibration  and  other header information
     accordingly:


        nmrPipe -fn EXT -x1 10.5ppm -xn 6.2ppm -sw


     Extract the central 90% of the data, update the header:


        nmrPipe -fn EXT -x1 5% -xn 95% -sw


     Extract the first 512 points from the given data:


        nmrPipe -fn EXT -xn 512


     In the following scheme, EXT -time is used to strip the zero
     padding  which was added by the spectrometer to extend a 500
     complex-point acquisition to 512 points on disk:

      bruk2pipe -in ser -noswap \
        -xN           1024    -yN         256  \
        -xT            500    -yT         128  \
        -xMODE     Complex    -yMODE  Complex  \
        -xSW       9259.26    -ySW    1330.23  \
        -xOBS       499.53    -yOBS     50.62  \
        -xCAR         4.79    -yCAR     116.5  \
        -xLAB           HN    -yLAB         N  \
        -ndim            2    -aq2D    States  \
       | nmrPipe -fn EXT -time                 \
         -out test.fid -verb -ov


BUGS
     Options to round up the extracted region  size  (-round  and
     -pow2)  will not work if the rounded size exceeds the origi-
     nal size of the data.

     The -sw flag is almost always required; this should probably
     be a default mode.