<!-- Creator : groff version 1.19.2 --> <!-- CreationDate: Wed Jul 14 08:43:44 2010 --> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta name="generator" content="groff -Thtml, see www.gnu.org"> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <meta name="Content-Style" content="text/css"> <style type="text/css"> p { margin-top: 0; margin-bottom: 0; } pre { margin-top: 0; margin-bottom: 0; } table { margin-top: 0; margin-bottom: 0; } </style> <title>BACKTRACKER</title> </head> <body bgcolor="#ffffff"> <h1 align=center>BACKTRACKER</h1> <a href="#NAME">NAME</a><br> <a href="#SYNOPSIS">SYNOPSIS</a><br> <a href="#DESCRIPTION">DESCRIPTION</a><br> <a href="#OPTIONS">OPTIONS</a><br> <a href="#EXAMPLES">EXAMPLES</a><br> <a href="#SEE ALSO">SEE ALSO</a><br> <a href="#REFERENCES">REFERENCES</a><br> <hr> <a name="NAME"></a> <h2>NAME</h2> <p style="margin-left:11%; margin-top: 1em">backtracker − Reconstruct points, flowlines and hotspot tracks</p> <a name="SYNOPSIS"></a> <h2>SYNOPSIS</h2> <p style="margin-left:11%; margin-top: 1em"><b>backtracker</b> [<i>infile(s)</i>] <b>−E</b><i>rotations.txt</i> | <b>−e</b><i>lon</i>/<i>lat</i>/<i>angle</i> [ <b>−A</b>[<i>young</i>/<i>old</i>] ] [ <b>−C</b> ] [ <b>−Df</b>|<b>b</b> ] [ <b>−H</b>[<b>i</b>][<i>nrec</i>] ] [ <b>−Lf</b>|<b>b</b><i>step</i> ] [ <b>−N</b><i>upper_age</i> ] [ <b>−Q</b><i>fixed_age</i> ] [ <b>−S</b><i>filestem</i> ] [ <b>−T</b><i>zero_age</i> ] [ <b>−V</b> ] [ <b>−W</b>[<b>a</b>|<b>t</b>] ] [ <b>−:</b>[<b>i</b>|<b>o</b>] ] [ <b>−b</b>[<b>i</b>|<b>o</b>][<b>s</b>|<b>S</b>|<b>d</b>|<b>D</b>[<i>ncol</i>]|<b>c</b>[<i>var1</i><b>/</b><i>...</i>]] ] [ <b>−m</b>[<b>i</b>|<b>o</b>][<i>flag</i>] ]</p> <a name="DESCRIPTION"></a> <h2>DESCRIPTION</h2> <p style="margin-left:11%; margin-top: 1em"><b>backtracker</b> reads (longitude, latitude, age) positions from <i>infiles</i> [or standard input] and computes rotated (x,y,t) coordinates using the specified rotation parameters. It can either calculate final positions [Default] or create a sampled track (flowline or hotspot track) between the initial and final positions. The former mode allows additional data fields after the first 3 columns which must have (longitude,latitude,age). See option <b>−:</b> on how to read (latitude,longitude,age) files.</p> <table width="100%" border=0 rules="none" frame="void" cellspacing="0" cellpadding="0"> <tr valign="top" align="left"> <td width="8%"></td> <td width="7%"></td> <td width="85%"> <p valign="top">No space between the option flag and the associated arguments. Use upper case for the option flags and lower case for modifiers.</p></td> </table> <p style="margin-left:11%;"><i>infile(s)</i></p> <p style="margin-left:22%;">Data file(s) to be projected. If not given, standard input is read.</p> <table width="100%" border=0 rules="none" frame="void" cellspacing="0" cellpadding="0"> <tr valign="top" align="left"> <td width="11%"></td> <td width="3%"> <p style="margin-top: 1em" valign="top"><b>−E</b></p> </td> <td width="4%"></td> <td width="82%"> <p style="margin-top: 1em" valign="top">Give file with rotation parameters. This file must contain one record for each rotation; each record must be of the following format:</p> </td> <tr valign="top" align="left"> <td width="11%"></td> <td width="3%"></td> <td width="4%"></td> <td width="82%"> <p valign="top"><i>lon lat tstart [tstop] angle</i> [ <i>khat a b c d e f g df</i> ]</p></td> </table> <p style="margin-left:22%; margin-top: 1em">where <i>tstart</i> and <i>tstop</i> are in Myr and <i>lon lat angle</i> are in degrees. <i>tstart</i> and <i>tstop</i> are the ages of the old and young ends of a stage. If <b>−C</b> is set then a total reconstruction rotation is expected and <i>tstop</i> is implicitly set to 0 and should not be specified in the file. If a covariance matrix <b>C</b> for the rotation is available it must be specified in a format using the nine optional terms listed in brackets. Here, <b>C</b> = (<i>g</i>/<i>khat</i>)*[ <i>a b d; b c e; d e f</i> ] which shows <b>C</b> made up of three row vectors. If the degrees of freedom (<i>df</i>) in fitting the rotation is 0 or not given it is set to 10000. Blank lines and records whose first column contains # will be ignored.</p> <table width="100%" border=0 rules="none" frame="void" cellspacing="0" cellpadding="0"> <tr valign="top" align="left"> <td width="11%"></td> <td width="3%"> <p style="margin-top: 1em" valign="top"><b>−e</b></p> </td> <td width="8%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Alternatively, specify the longitude, latitude, and opening angle (all in degrees and separated by /) for a single total reconstruction rotation that should be applied to all input points.</p> </td> </table> <a name="OPTIONS"></a> <h2>OPTIONS</h2> <table width="100%" border=0 rules="none" frame="void" cellspacing="0" cellpadding="0"> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−A</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Used in conjunction with <b>−Lb</b>|<b>f</b> to limit the track output to those sections whose predicted ages lie between the specified <i>young</i> and <i>old</i> limits. If <b>−LB</b>|<b>F</b> is used instead then the limits apply to the stage ids (id 1 is the youngest stage). If no limits are specified then individual limits for each record are expected in columns 4 and 5 of the input file.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−C</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Expect Total Reconstruction Rotations rather than Forward Stage Rotations [Default]. File format is similar to the stage pole format except that the <i>tstart</i> column is not present (assumed to be 0 Ma). Requires <b>−E</b>.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−D</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Set the direction to go: <b>−Df</b> will go backward in time (from younger to older positions), while <b>−Db</b> will go forward in time (from older to younger positions) [Default]. Note: For <b>−Db</b> you are specifying the age at the given location, whereas for <b>−Df</b> you are not; instead you specify the age at the reconstructed point.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−H</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Input file(s) has header record(s). If used, the default number of header records is <b><A HREF="gmtdefaults.html#N_HEADER_RECS">N_HEADER_RECS</A></b>. Use <b>−Hi</b> if only input data should have header records [Default will write out header records if the input data have them]. Blank lines and lines starting with # are always skipped.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−L</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Specify a sampled path between initial and final position: <b>−Lf</b> will draw particle flowlines, while <b>−Lb</b> will draw backtrack (hotspot track) paths. Append sampling interval in km. If <i>step</i> < 0 then only the rotation times will be returned. When <b>−LF</b> or <b>−LB</b> is used, the third output column will contain the stage id (1 is youngest) [Default is along-track predicted ages]. You can control the direction of the paths by using <b>−D</b>.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−N</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Set the maximum age to extend the oldest stage rotation back in time [Default is no extension].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−Q</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Assign a fixed age to all positions. Only lon, lat input is expected [Default expects longitude, latitude, age]. Useful when the input are points defining isochrons.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−S</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">When <b>−L</b> is set, the tracks are normally written to stdout as a multisegment file. Specify a <i>filestem</i> to have each track written to <i>filestem.#</i>, where <i>#</i> is the track number. The track number is also copied to the 4th output column.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−T</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Set the current time [Default is 0 Ma].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−V</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−W</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Rotates the given input (lon,lat,t) and calculates the confidence ellipse for the projected point. The input point <i>must</i> have a time coordinate that exactly matches a particular finite rotation time, otherwise the point will be skipped. Append <b>t</b> or <b>a</b> to output time or angle, respectively, after the projected lon, lat. After these 2-3 items, we write azimuth, major, minor (in km) for the 95% confidence ellipse. See <b>−D</b> for the direction of rotation.</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−:</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Toggles between (longitude,latitude) and (latitude,longitude) input and/or output. [Default is (longitude,latitude)]. Append <b>i</b> to select input only or <b>o</b> to select output only. [Default affects both].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−bi</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Selects binary input. Append <b>s</b> for single precision [Default is <b>d</b> (double)]. Uppercase <b>S</b> or <b>D</b> will force byte-swapping. Optionally, append <i>ncol</i>, the number of columns in your binary input file if it exceeds the columns needed by the program. Or append <b>c</b> if the input file is netCDF. Optionally, append <i>var1</i><b>/</b><i>var2</i><b>/</b><i>...</i> to specify the variables to be read. [Default is 3 input columns].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−bo</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Selects binary output. Append <b>s</b> for single precision [Default is <b>d</b> (double)]. Uppercase <b>S</b> or <b>D</b> will force byte-swapping. Optionally, append <i>ncol</i>, the number of desired columns in your binary output file. [Default depends on settings].</p></td> <tr valign="top" align="left"> <td width="11%"></td> <td width="4%"> <p style="margin-top: 1em" valign="top"><b>−m</b></p> </td> <td width="7%"></td> <td width="78%"> <p style="margin-top: 1em" valign="top">Multiple segment file(s). Segments are separated by a special record. For ASCII files the first character must be <i>flag</i> [Default is ’>’]. For binary files all fields must be NaN and <b>−b</b> must set the number of output columns explicitly. By default the <b>−m</b> setting applies to both input and output. Use <b>−mi</b> and <b>−mo</b> to give separate settings to input and output.</p> </td> </table> <a name="EXAMPLES"></a> <h2>EXAMPLES</h2> <p style="margin-left:11%; margin-top: 1em">To backtrack the (x,y,t) points in the file seamounts.d to their origin (presumably the hotspot), using the DC85.d Euler poles, run</p> <p style="margin-left:11%; margin-top: 1em"><b>backtracker</b> seamounts.d <b>−Db −E</b>DC85.d > newpos.d</p> <p style="margin-left:11%; margin-top: 1em">To project flowlines forward from the (x,y,t) points stored in several 3-column, binary, double precision files, run</p> <p style="margin-left:11%; margin-top: 1em"><b>backtracker</b> points.* <b>−Df −E</b>DC85.d <b>−Lf</b>25 <b>−bo −bi</b><i>3</i> > lines.b</p> <p style="margin-left:11%; margin-top: 1em">This file can then be plotted with <b>psxy −M</b>.</p> <a name="SEE ALSO"></a> <h2>SEE ALSO</h2> <p style="margin-left:11%; margin-top: 1em"><i><A HREF="GMT.html">GMT</A></i>(1), <i><A HREF="project.html">project</A></i>(1), <i><A HREF="mapproject.html">mapproject</A></i>(1), <i><A HREF="hotspotter.html">hotspotter</A></i>(1), <i><A HREF="originator.html">originator</A></i>(1)</p> <a name="REFERENCES"></a> <h2>REFERENCES</h2> <p style="margin-left:11%; margin-top: 1em">Wessel, P., 1999, "Hotspotting" tools released, EOS Trans. AGU, 80 (29), p. 319.</p> <hr> </body> </html>