Re: checking if variable is defined

[Bernard Puc <bpuc(at)va.aetc.com>]

Dominik wrote:
> 
> Helle there,
> 
> I would like to plot a variable, but only if it is existing. When the
> Variable is undefined, nothing should happen. So I am searching for an
> expression for the if  statement. Does anybody know an expression like:
> if ( vaiable_name existing) then...


One way to do this is with the N_ELEMENTS() function:

if (n_elements( variable ) GT 0) then print,'Variable exists'

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