• To: mathgroup at smc.vnet.net
• Subject: [mg17022] Re: [mg16997] ParametricPlot help please
• From: BobHanlon at aol.com
• Date: Wed, 14 Apr 1999 02:11:45 -0400
• Sender: owner-wri-mathgroup at wolfram.com

```In a message dated 4/10/99 5:39:36 AM, robpeterson at iname.com writes:

>Some time ago several kind souls on this ng helped me do some conformal
>transformation plots (this one is part of the curves describing the fields
>in a parallel plate capacitor).  We used a series of ParametricPlots.
>Now
>I would like to understand how this worked - maybe I can learn something
>about Mathematica.  I think I get the use of Map[] but I am stuck on the
>use of
>ParametricPlot[#1,.....].  I have looked high and low and I do not find
>any
>mention of the #1 parameter.  If I ever get thru this, I'll start trying
>to
>

Rob,

See on-line help or manual for Slot and Function.  # represents the first
argument supplied to a pure function and #n represents the n-th argument.
Consequently, # and #1 are the same.   ## represents the  sequence of all
arguments supplied.

f[#]& /@ {a, b, c, d}

{f[a], f[b], f[c], f[d]}

f[##, #2]& [x,y,z]

f[x, y, z, y]

#^2& /@  {a, b, c, d}

{a^2, b^2, c^2, d^2}

You can also use parts of arguments

f[#[[1]], #[[2]]]& /@ {{a,b}, {c,d}}

{f[a, b], f[c, d]}

Bob Hanlon

```

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