READTOPO is the jdata module of jLab.

 READTOPO  Read one-minute topography data from Smith and Sandwell. 
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    [TOPO,LAT,LON]=READTOPO(REGION) extracts regional topography from the
    the one-minute Smith and Sandwell global database version 18.1.  This 
    file is included with JDATA, available from at http://www.jmlilly.net.
 
    REGION is an array of the form REGION=[WEST EAST SOUTH NORTH] which  
    indicates the *edges* of the desired domain.  Longitudes can be 
    specified either on the interval [0,360] or the interval [-180,180]. 
 
    The region may overlap the prime meridian or the dateline.  Region
    boundaries are interpreted to exclude the poles. 
  
    TOPO is a matrix of topography in units of kilometers and is positive 
    for above sea level, and negative for below sea level.  
 
    LON is a row vector of longitudes and LAT a column vector of latitudes.
 
    LAT and LON output by READTOPO are *grid-centered*, that is, they
    indicate midpoints of the topography cells. LON is uniformly spaced, 
    but LAT is non-uniformly spaced, with bin sizes decreasing poleward.
 
    Note that the Smith and Sandwell database is defined only for latitudes 
    between -80.738 and 80.738.
 
    Topography at higher northern latitudes is found in the IBCAO dataset,
    see ABOUT_IBCAO.  A merged 1/6th degree version of both datasets,
    called JTOPO, is is distributed with JLAB; see ABOUT_JTOPO for details.
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    Interpolation
 
    [TOPO,LAT,LON]=READTOPO(REGION,DLAT,DLON) optionally linearly 
    interpolates the one-minute (1/60 degree) topographic data to a 
    different resolution, specified by DLAT and DLON, in degrees.   
 
    READTOPO(REGION,DLAT) with DLON omitted sets DLON=DLAT.
 
    This is useful for interpolating the high-resolution Smith and Sandwell
    dataset to a coarser resolution. 
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    Alternate path
 
    By default, READTOPO looks for the topography file topo_18.1.img in 
    the JLAB directory.  
 
    [TOPO,LAT,LON]=READTOPO(DIRNAME,REGION...) alternatively specifies  
    DIRNAME as the path to the parent directory of the file topo_18.1.img. 
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    Data and documentation
 
    The original location for the Smith and Sandwell Global Topography
     Dataset v. 18.1, file 'topo_18.1.img' is
 
        http://topex.ucsd.edu/WWW_html/mar_topo.html.
 
    The reference for the Smith and Sandwell Database is
 
       Smith, W. H. F., and D. T. Sandwell, Global seafloor topography 
       from satellite altimetry and ship TOPO soundings, Science, v. 277, 
       p. 1957-1962, 26 Sept., 1997.
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    License and Copyright 
 
    The data file topo_18.1.img is distributed with JDATA for RESEARCH AND 
    NON-PROFIT USE ONLY, in accordance with the copyright statement for the
    Smith and Sandwell dataset.  For details, type 'help topo_copyright'.
 
    You are free to use and redistribute READTOPO under the terms in the
    JLAB license, http://www.jmlilly.net/doc/jlab/jlab_license.html.
 
    READTOPO is self-contained, although tests and sample figure require 
    JLAB to run.  JLAB is available from http://www.jmlilly.net.
 
    Send comments, questions, and bug reports to 'eponym@jmlilly.net'.
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    See also ABOUT_IBCAO, and JTOPO, REGIONPLOT, and TOPOPLOT in JLAB.
 
    'readtopo --f' generates the sample figure shown above.
    'readtopo --t' runs some tests.
 
    Usage: [topo,lat,lon]=readtopo([west east south north]);
           [topo,lat,lon]=readtopo(dirname,[west east south north]);
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    This is part of JLAB --- type 'help jlab' for more information
    (C) 2006--2015 J.M. Lilly --- type 'help jlab_license' for details

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