B<LT, LE, GT, GE, EQ, NE>
-I<Note: NE is not yet implemented>
-
Pop two elements from the stack, compare them for the selected condition
and return 1 for true or 0 for false. Comparing an I<unknown> or an
I<infinite> value will always result in 0 (false).
B<UN, ISINF>
-I<Note: ISINF is not yet implemented>
-
Pop one element from the stack, compare this to I<unknown> respectively
to I<positive or negative infinity>. Returns 1 for true or 0 for false.
step. This allows you to do calculations across the data. This
function cannot be used in B<VDEF> instructions.
+B<PREV(vname)>
+
+Pushes an I<unknown> value if this is the first value of a data
+set or otherwise the result of vname variable at the previous time
+step. This allows you to do calculations across the data. This
+function cannot be used in B<VDEF> instructions.
+
+B<COUNT>
+
+Pushes the number 1 if this is the first value of the data set, the
+number 2 if it is the second, and so on. This special value, allows
+you to make calculations based on the position of the value within
+the data set. This function cannot be used in B<VDEF> instructions.
+
Z<>
=item Time
=item MAXIMUM, MINIMUM, AVERAGE
-Return the corresponding value
+Return the corresponding value, MAXIMUM and MINIMUM also return
+the first occurance of that value in the time component.
+
+Example: C<VDEF:avg=mydata,AVERAGE>
Z<>
=item LAST, FIRST
-Return the last,first value including its time
+Return the last,first value including its time. The time for
+FIRST is actually the start of the corresponding interval, where
+LASTs time component returns the end of the corresponding interval.
+
+Example: C<VDEF:first=mydata,FIRST>
+
+Z<>
+
+=item TOTAL
+
+Returns the rate from each defined timeslot multiplied with the
+step size. This can for instance return total bytes transfered
+when you have logged bytes per second. The time component returns
+the amount of seconds
+
+Example: C<VDEF:total=mydata,TOTAL>
Z<>
-=item PERCENTILE
+=item PERCENT
Should follow a B<DEF> or B<CDEF> I<vname>. This I<vname> is popped,
another number is popped which is a certain percentage (0..100). The
I<percentage> percent of the values is lower or equal than the result.
I<Unknown> values are considered lower than any finite number for this
purpose so if this operator returns an I<unknown> you have quite a lot
-of them in your data...
+of them in your data. B<Inf>inite numbers are lesser, or more, than the
+finite numbers and are always more than the I<Unknown> numbers.
-Example: C<VDEF:perc95=95,mydata,PERCENTILE>
+Example: C<VDEF:perc95=mydata,95,PERCENT>
=back