Re: Creating Variables in Programs

[Craig Markwardt <craigmnet(at)astrog.physics.wisc.edu>]

Martin Schultz <mgs@io.harvard.edu> writes:
> 
> Perry Phillips wrote:
> > 
> > Does anyone know of a way to create a new array under program control, ie
> > create a string and use that string to make an array. As far as I can see
> > this is impossible in IDL?
> > 
> > --
> > Perry Phillips                p.phillips@mail.utexas.edu
> 
> 
> here's a quick example
> 
> 
> IDL> r=execute('a=fltarr(200)')
> IDL> help,a
> A               FLOAT     = Array[200]
> 

There is a "gotcha."  in the case of a compiled procedure, the
variable "a" must have already been defined.  The following is usually
sufficient:

   A = 0
   ...
   R = EXECUTE('A=FLTARR(200)')

The IDL internal compiler needs to know that "A" exists before it can
be assigned to in an EXECUTE statement.  The same applies for
restoring variables: all the variables in the SAVE file must be
predefined in the procedure.  Assigning zero to them is fine.

Craig

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Craig B. Markwardt, Ph.D.         EMAIL: craigmnet@astrog.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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