[rrd-users] rpn equation
linux at thehobsons.co.uk
Sun Nov 2 08:40:31 CET 2008
R Dicaire wrote:
> > If that is the case, tehn you can use an "if" expression to set it to
>> zero instead.
>Indeed that is the case, and now I recall a discussion on that very
>subject...could you give an example of an if statement please?
I think what you need is :
Which you read as :
a,UN = check if a is known or not - returns true if a is unknown
a,0,(a is unknown),IF = if a is unknown then leave 0 on the stack,
else leave a on the stack.
Just substitute your real data source for a, and use this expression
where you would otherwise have used the real data source.
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