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Re: Creating Variables in Programs [message #12193 is a reply to message #12188]

Fri, 10 July 1998 00:00

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

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

--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@astrog.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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		Re: Creating Variables in Programs By: Martin Schultz on Fri, 10 July 1998 00:00
		Re: Creating Variables in Programs By: Craig Markwardt on Fri, 10 July 1998 00:00
		Re: Creating Variables in Programs By: Martin Schultz on Fri, 10 July 1998 00:00

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