Re: MAKE_ARRAY question

[Paul van Delst <paul.vandelst(at)noaa.gov>]

Paul van Delst wrote:
> 
> Hi there,
> 
> I want to create an array that by default should be FLOAT but can be specified as DOUBLE
> by the user as a keyword input to a function. Instead of the following:
> 
> FUNCTION my_func, n_pts, double = double
> 
>   IF ( KEYWORD_SET( double ) ) THEN $
>     x = MAKE_ARRAY( n_pts, /DOUBLE, /NOZERO ) $
>   ELSE $
>     x = MAKE_ARRAY( n_pts, /FLOAT, /NOZERO )
> 
> .....
> 
> END
> 
> can I rely on the fact that NO type keywords to MAKE_ARRAY means default FLOAT? I.e. :
> 
> FUNCTION my_func, n_pts, double = double
> 
>   x = MAKE_ARRAY( n_pts, DOUBLE = double, /NOZERO )
> 
> .....
> 
> END
> 
> The MAKE_ARRAY documentation does not specifically state that the default array created is
> a FLOAT. Does anyone know if this *is* documented anywhere so I'm not setting my function
> up (which I use *a lot*) to fall in a heap when IDL 5.5+ is released and RSI happened to
> decide a default LONG would be better?
> 
> Or is there some other natty way to do this?

One could also do:

  x = MAKE_ARRAY( n_pts, VALUE = 0.0, DOUBLE = double )

i.e value = float if double is not set, but I want to avoid the value assignation. The
array can be quite large (many millions of points x 2) hence the /NOZERO. The performance
hit of using the VALUE keyword is noticeable (the /NOZERO has no effect if VALUE is used).

paulv

-- 
Paul van Delst           A little learning is a dangerous thing;
CIMSS @ NOAA/NCEP        Drink deep, or taste not the Pierian spring;
Ph: (301)763-8000 x7274  There shallow draughts intoxicate the brain,
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paul.vandelst@noaa.gov                   Alexander Pope.