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Re: Question on defaults in positional arguments

  • To: mathgroup at smc.vnet.net
  • Subject: [mg112593] Re: Question on defaults in positional arguments
  • From: "David Park" <djmpark at comcast.net>
  • Date: Wed, 22 Sep 2010 01:56:35 -0400 (EDT)

If Mathematica cannot distinguish between the arguments by their types, then
you must include all the leading optional arguments of the same type.

Clear[f];
f[x_: 1, y_: 2, z_: 3] := {x, y, z} 

f[1, 5] 

{1, 5, 3} 


But...

Clear[f]
f[x_String: "Type1", y_Integer: 2, z_Real: 3.0] := {x, y, z} 

f[5] 

{"Type1", 5, 3.}


David Park
djmpark at comcast.net
http://home.comcast.net/~djmpark/  



From: NP [mailto:nomplume69 at gmail.com] 


Hi,

I was wondering if there was a way in selectively specifying some of
the arguments of a function (rest remaining default). For instance,
consider
Clear[f, x, y,z];
f[x_: 1, y_: 2,z_:3] := {x, y}
f[5]

{5,2,3}

Here the default values of y and z are automatically used. How can I
call f so that, for example,  the default value of x  and z are used
instead?

Thanks,

NP



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