Imported upstream version 1.4~rc2.

[pkg-rrdtool.git] / doc / rrdgraph_data.1

diff --git a/doc/rrdgraph_data.1 b/doc/rrdgraph_data.1
index d0e5b20a6fd6e12c04b98184f9971fb4dd187c10..7c9538c3a739a24c1ae1ec94379edd830329d823 100644 (file)
--- a/doc/rrdgraph_data.1
+++ b/doc/rrdgraph_data.1
@@ -1,4 +1,4 @@
-.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
+.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14
 .\"
 .\" Standard preamble:
 .\" ========================================================================
@@ -25,11 +25,11 @@
 ..
 .\" Set up some character translations and predefined strings.  \*(-- will
 .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
-.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
-.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
-.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
-.\" nothing in troff, for use with C<>.
-.tr \(*W-
+.\" double quote, and \*(R" will give a right double quote.  | will give a
+.\" real vertical bar.  \*(C+ will give a nicer C++.  Capital omega is used to
+.\" do unbreakable dashes and therefore won't be available.  \*(C` and \*(C'
+.\" expand to `' in nroff, nothing in troff, for use with C<>.
+.tr \(*W-|\(bv\*(Tr
 .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
 .ie n \{\
 .    ds -- \(*W-
@@ -129,7 +129,7 @@
 .\" ========================================================================
 .\"
 .IX Title "RRDGRAPH_DATA 1"
-.TH RRDGRAPH_DATA 1 "2008-03-15" "1.3.0" "rrdtool"
+.TH RRDGRAPH_DATA 1 "2009-04-29" "1.3.99909060808" "rrdtool"
 .SH "NAME"
 rrdgraph_data \- preparing data for graphing in rrdtool graph
 .SH "SYNOPSIS"
@@ -152,7 +152,7 @@ Variable names (\fIvname\fR) must be made up strings of the following characters
 \&\f(CW\*(C`A\-Z, a\-z, 0\-9, \-,_\*(C'\fR and a maximum length of 255 characters.
 .PP
 When picking variable names, make sure you do not choose a name that is
-already taken by an \s-1RPN\s0 operator. A save bet it to use lowercase or
+already taken by an \s-1RPN\s0 operator. A safe bet it to use lowercase or
 mixedcase names for variables since operators will always be in uppercase.
 .SH "DEF"
 .IX Header "DEF"
@@ -204,7 +204,7 @@ elements.
 .PP
 Example: \f(CW\*(C`VDEF:avg=mydata,AVERAGE\*(C'\fR
 .PP
-Note that currently only agregation functions work in \s-1VDEF\s0 rpn expressions.
+Note that currently only aggregation functions work in \s-1VDEF\s0 rpn expressions.
 Patches to change this are welcome.
 .SH "CDEF"
 .IX Header "CDEF"
@@ -217,6 +217,32 @@ data point. The resulting \fIvname\fR can then be used further on in
 the script, just as if it were generated by a \fB\s-1DEF\s0\fR instruction.
 .PP
 Example: \f(CW\*(C`CDEF:mydatabits=mydata,8,*\*(C'\fR
+.SH "About CDEF versus VDEF"
+.IX Header "About CDEF versus VDEF"
+At some point in processing, \fBRRDtool\fR has gathered an array of rates
+ready to display.
+.PP
+\&\fB\s-1CDEF\s0\fR works on such an array.  For example, \fICDEF:new=ds0,8,*\fR
+would multiply each of the array members by eight (probably
+transforming bytes into bits). The result is an array containing the
+new values.
+.PP
+\&\fB\s-1VDEF\s0\fR also works on such an array but in a different way.  For
+example, \fIVDEF:max=ds0,MAXIMUM\fR would scan each of the array members
+and store the maximum value.
+.Sh "When do you use \fB\s-1VDEF\s0\fP versus \fB\s-1CDEF\s0\fP?"
+.IX Subsection "When do you use VDEF versus CDEF?"
+Use \fB\s-1CDEF\s0\fR to transform your data prior to graphing.  In the above
+example, we'd use a \fB\s-1CDEF\s0\fR to transform bytes to bits before
+graphing the bits.
+.PP
+You use a \fB\s-1VDEF\s0\fR if you want \fImax(1,5,3,2,4)\fR to return five which
+would be displayed in the graph's legend (to answer, what was the
+maximum value during the graph period).
+.PP
+If you want to apply 'complex' operations to the result of a \s-1VDEF\s0 you have
+to use a \s-1CDEF\s0 again since VDEFs only look like \s-1RPN\s0 expressions, they aren't
+realy.
 .SH "SEE ALSO"
 .IX Header "SEE ALSO"
 rrdgraph gives an overview of how \fBrrdtool graph\fR works.
@@ -229,4 +255,5 @@ Make sure to read rrdgraph_examples for tips&tricks.
 .IX Header "AUTHOR"
 Program by Tobias Oetiker <tobi@oetiker.ch>
 .PP
-This manual page by Alex van den Bogaerdt <alex@ergens.op.het.net>
+This manual page by Alex van den Bogaerdt <alex@vandenbogaerdt.nl>
+with corrections and/or additions by several people