fix stak+nan error ... Scott Mace <smace@intt.ORG>

[rrdtool.git] / doc / rrdgraph_rpn.src

diff --git a/doc/rrdgraph_rpn.src b/doc/rrdgraph_rpn.src
index 7952a3f..a8c4b11 100644 (file)
--- a/doc/rrdgraph_rpn.src
+++ b/doc/rrdgraph_rpn.src
@@ -42,16 +42,12 @@ would do C<a = b, 3, +, 5, *> and need no parentheses.
 
 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.
 
@@ -127,6 +123,13 @@ set or otherwise the result of this B<CDEF> at the previous time
 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.
+
 Z<>
 
 =item Time