From: André Marascalchi Zenun <andre.zenun@gm...>  20081023 23:11:52

hey Stan, Well I have readed this manual but I still doesn't understand well how do you evaluate this expression! I can perfectly understand this torrus RPN expression: POP,LTIME,86400,%,DUP,79200,GE,EXC,21600,LE,+,INF,UNKN,IF But I'm unable to completely evaluate this : {(300)},10,*,GT,{},{(300)},10,/,LT,OR {(300)} = value on the RRD database of the 5min ago {} = I don't know what this is, this is not on the man page GT = Pop two elements from the stack, compare them for the selected condition and return 1 for true or 0 for false {(300)},10,*,GT,{},{(300)},10,/,LT,OR *50,10,**,GT,{},50,10,/,LT,OR 500,GT,{},50,10,/,LT,OR Using the explanation of the rrdtool RPN page, GT will not evaluate this because it needs 2 values! Where is my mistake? Thanks 2008/10/23 Stanislav Sinyagin <ssinyagin@...> > hey Andre, > > read that funny manual :) > > http://torrus.org/rpnexpr.pod.html > > it also links back to the original RRDtool PPN. > > also might be useful to have a glance over > http://en.wikipedia.org/wiki/Reverse_Polish_Notation > > > > > > > ________________________________ > From: André Marascalchi Zenun <andre.zenun@...> > To: torrususers@... > Sent: Thursday, October 23, 2008 10:26:04 PM > Subject: [torrususers] RPN expression evaluation > > Hello all, > > I'm a bit confused on how to evaluate an RPN expression described on the > torrus website! > The expression is this one: > > {(300)},10,*,GT,{},{(300)},10,/,LT,OR > > This expression as described on the website is to detect a variation of 10 > times the last value. > Can some one explain how this will be evaluated? I want adapt it to some > needs here! > I know a little about RPN but some symbols like {} and {(300)} is > confusing me on how to evaluate it! > > Thanks a lot! > > 