It's entirely separate of the main point, but Maarten's example contains a bug. The body of the program should be
c_local `1' = (`2')^2
For further explanation, see
FAQ . . . . . . . . . . . . . . The use of macros with the power operator
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W. Gould
12/99 I coded `a'^2 and got the wrong sign. Why?
<http://www.stata.com/support/faqs/lang/macpow.html>
Nick
[email protected]
Maarten buis
--- On Wed, 18/2/09, Fabrice <[email protected]> wrote:
> how does one write a *function*, i.e. a program that returns
> a value, and that can be called like local y = fct(x), where
> x and y are numbers or strings. <snip>
> FYI, I know about r-type vs. e-type program, and know how to
> store results to return to main program.
Short answer: you can't.
Longer answer:
You can leave a local behind using the not documented
-c_local- command, so in the example below the program
square leaves behind a local called foo
*------------ begin example ---------
capture program drop square
program define square
c_local `1' = `2'^2
end
square foo 2
di `foo'
*------------ end example -----------
You can make a function like program that works with
the -egen- command, but this will only make variables.
To do so call your program _g<whatever>.ado, to create
the whatever "function". You can look at
-viewsource _gcount.ado- to see an example of such a
program. Alternatively you can make a function in Mata,
but that will only function as a function within Mata.
*
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* http://www.stata.com/help.cgi?search
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