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Re: How to judge a Function's parameters ? [message #66271]

Thu, 07 May 2009 15:02

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

Hu wrote:
> Hi,folks,
>
> I created a function 'RectArea' to calculate the rectangle area, and
> two parameters, side a and b, are needed when the function is
> employed.
>
> I want to do something like this: if a and b are omitted by the user,
> then the function will use the default values.
>
> But, How can I judge that the parameters are omitted?
>
> Thanks
>
> function RectArea,a,b
> return,a*b
> end

Use N_ELEMENTS to determine if a particular parameter is omitted. I
usually do something like the following:

function RectArea, a, b
compile_opt strictarr

_a = n_elements(a) eq 0L ? 1.0 : a
_b = n_elements(a) eq 0L ? 1.0 : b

return, _a * _b
end

I don't do:

if (n_elements(a) eq 0L) then a = 1.0

because I don't want change an input variable from the user.

Mike
--
www.michaelgalloy.com
Associate Research Scientist
Tech-X Corporation

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[Message index]

		Re: How to judge a Function's parameters ? By: Michael Galloy on Thu, 07 May 2009 15:02
		Re: How to judge a Function's parameters ? By: Paul Van Delst[1] on Thu, 07 May 2009 15:01
		Re: How to judge a Function's parameters ? By: Paul Van Delst[1] on Thu, 07 May 2009 15:32

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