new CDEF functions for predictions PREDICT and PREDICTSIGMA

[rrdtool.git] / doc / cdeftutorial.pod

diff --git a/doc/cdeftutorial.pod b/doc/cdeftutorial.pod
index fc24a34..72d1807 100644 (file)
--- a/doc/cdeftutorial.pod
+++ b/doc/cdeftutorial.pod
@@ -4,8 +4,13 @@ cdeftutorial - Alex van den Bogaerdt's CDEF tutorial
 
 =head1 DESCRIPTION
 
-If you provide a question, I will try to provide an answer in the next
-release of this tutorial. No feedback equals no changes! Additions to
+Intention of this document: to provide some examples of the commonly
+used parts of RRDtool's CDEF language.
+
+If you think some important feature is not explained properly, and if
+adding it to this document would benefit most users, please do ask me
+to add it.  I will then try to provide an answer in the next release
+of this tutorial.  No feedback equals no changes! Additions to
 this document are also welcome.  -- Alex van den Bogaerdt
 E<lt>alex@ergens.op.het.netE<gt>
 
@@ -612,7 +617,7 @@ numbers (or zero) only.
 Let's compile the complete CDEF:
 
        DEF:ds0=router1.rrd:AVERAGE
-       CDEF:ds0modified=TIME,begintime,GE,TIME,endtime,LE,*,UNKN,ds0,IF
+       CDEF:ds0modified=TIME,begintime,GT,TIME,endtime,LE,*,ds0,UNKN,IF
 
 This will return the value of ds0 if both comparisons return true. You
 could also do it the other way around:
@@ -744,7 +749,7 @@ as follows:
    5. push 32
    6. push function "plus" and process it
       the stack contains now the temperature in Fahrenheit
-   
+
 =head2 Changing unknown into zero
 
    rrdtool graph demo.png --title="Demo Graph" \