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<div>I may be wrong, but I don't believe that you can have a CDEF refer to a VDEF -- only to a DEF or a CDEF. A VDEF can be defined over a DEF or a CDEF but with no complex calculations. This is because a VDEF is a single value (possibly with a time) but
a CDEF (like a DEF) is a full set of data over the time interval.</div>
<div> </div>
<div>Steve</div>
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<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma"><strong>Steve Shipway</strong></div>
<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma">University of Auckland ITS</div>
<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma"><em>UNIX Systems Design Lead</em></div>
<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma"><a href="mailto:s.shipway@auckland.ac.nz">s.shipway@auckland.ac.nz</a></div>
<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma">Ph: +64 9 373 7599 ext 86487</div>
<div style="FONT-SIZE: 13px; FONT-FAMILY: Tahoma"><em></em> </div>
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<div id="divRpF959824" style="DIRECTION: ltr"><font face="Tahoma" color="#000000" size="2"><b>From:</b> rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch [rrd-users-bounces+s.shipway=auckland.ac.nz@lists.oetiker.ch] on behalf of Rob Newman [rlnewman@ucsd.edu]<br>
<b>Sent:</b> Thursday, 11 November 2010 2:03 p.m.<br>
<b>To:</b> rrd-users@lists.oetiker.ch<br>
<b>Subject:</b> [rrd-users] Concatenated VDEF and CDEF commands in a rrdtool graph cmd<br>
</font><br>
</div>
<div></div>
<div>Hi there,
<div><br>
</div>
<div>Does anyone know why this fails:</div>
<div><br>
</div>
<div>
<div><font class="Apple-style-span" face="Courier">rrdtool graph /path/to/outputimage/rrd.png \</font></div>
<div><font class="Apple-style-span" face="Courier"> --interlaced --imgformat PNG --end 1289434618 --start 1286756217 \</font></div>
<div><font class="Apple-style-span" face="Courier"> --width 600 --height 200 --title 'TEST' \</font></div>
<div><font class="Apple-style-span" face="Courier"> DEF:dt=/path/to/dt.rrd:dt:AVERAGE \</font></div>
<div><font class="Apple-style-span" face="Courier"> VDEF:dtfoo=dt,MAXIMUM \</font></div>
<div><font class="Apple-style-span" face="Courier"> CDEF:dtmaxdiff=dtfoo,16,- \</font></div>
<div><font class="Apple-style-span" face="Courier"> LINE1:dtmaxdiff#990000:'TESTFOO' \</font></div>
<div><font class="Apple-style-span" face="Courier"> GPRINT:dt:LAST:'Latest value for TESTFOO\: %4.0lf%s\j'</font></div>
<div><br>
</div>
<div>The output I get from rrdtool is:</div>
<div><br>
</div>
<div><font class="Apple-style-span" face="Courier">ERROR: rpn expressions without DEF or CDEF variables are not supported</font></div>
<div><br>
</div>
<div>If I try and add backslashes to the path (a la <a href="http://www.mrtg.org/rrdtool/doc/rrdgraph_rpn.en.html" target="_blank">http://www.mrtg.org/rrdtool/doc/rrdgraph_rpn.en.html</a>, note between the VDEF and CDEF rpn command there is not a carriage return
anymore, just whitespace and a backslash):</div>
<div>
<div><font class="Apple-style-span" face="Courier"><br>
</font></div>
<div><font class="Apple-style-span" face="Courier">rrdtool graph /path/to/outputimage/rrd.png \</font></div>
<div><font class="Apple-style-span" face="Courier"> --interlaced --imgformat PNG --end 1289434618 --start 1286756217 \</font></div>
<div><font class="Apple-style-span" face="Courier"> --width 600 --height 200 --title 'TEST' \</font></div>
<div><font class="Apple-style-span" face="Courier"> DEF:dt=/path/to/dt.rrd:dt:AVERAGE \</font></div>
<div><font class="Apple-style-span" face="Courier"> VDEF:dtfoo=dt,MAXIMUM \ </font><span class="Apple-style-span" style="FONT-FAMILY: Courier">CDEF:dtmaxdiff=dtfoo,16,- \</span></div>
<div><font class="Apple-style-span" face="Courier"> LINE1:dtmaxdiff#990000:'TESTFOO' \</font></div>
<div><font class="Apple-style-span" face="Courier"> GPRINT:dt:LAST:'Latest value for TESTFOO\: %4.0lf%s\j'</font></div>
</div>
<div><br>
</div>
<div>I now get the output:</div>
<div><br>
</div>
<div><font class="Apple-style-span" face="Courier">ERROR: Could not make sense out of ' CDEF:dtmaxdiff=dtfoo,16,-'</font></div>
<div><br>
</div>
<div>What I want is to find the maximum value for the data set ('dtfoo = dt,MAXIMUM'), then take that value and subtract 16 from it (dtmaxdiff = dtfoo,16,-), then plot that value.</div>
<div><br>
</div>
<div>Any ideas why both of these fail?</div>
<div><br>
</div>
<div>Thanks in advance,</div>
<div>- Rob</div>
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