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Re: Mathematica Graphics Primitives

  • To: mathgroup at smc.vnet.net
  • Subject: [mg41326] Re: [mg41283] Mathematica Graphics Primitives
  • From: Bobby Treat <drmajorbob at mailblocks.com>
  • Date: Wed, 14 May 2003 08:19:45 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

That code works perfectly at my machine.  I'm using version 4.2.1, but 
I don't think that's the problem.

It seems likely that you tried to use Arrow before loading the package. 
  Once you have done that, it's too late to load it, as Arrow in the 
Global context will "shadow" the one you want to use.  Quit and start 
over, and if you still have a problem -- I can't imagine what it is!

Bobby

-----Original Message-----
From: jprusa <jprusa at bellsouth.net>
To: mathgroup at smc.vnet.net
Subject: [mg41326] [mg41283] Mathematica Graphics Primitives

Hello:

I am interested in plotting vectors, and have tried the code suggested
in
  the Mathematica 4 Standard Add-on Packages GuideBook (section 6,
Graphics):

<< Graphics`Arrow`

Show[Graphics[
     Table[Arrow[{0, 0}, x {Sin[x], Cos[x]}
             HeadScaling -> Absolute],
       {x, 0, 2* Pi, .3}]],
   	PlotRange -> All]

and it doesn't work! Instead of getting the nice series of vectors
shown on the bottom of p. 135,
I get:

 From In[59]:=
Graphics::gprim: \
Arrow[{0,0}, {<<1>>} -> Absolute] was \
encountered where a Graphics primitive or directive was expected.

 From In[59]:=
Graphics::gprim: Arrow[{0,0}, {<<1>>} -> Absolute] \
was encountered where a Graphics primitive or directive was expected.

 From In[59]:=
Graphics::gprim: Arrow[{0,0}, {<<1>>} ] was \
encountered where a Graphics primitive or directive was expected.

 From In[59]:=
General::stop: Further output of Graphics::gprim will be suppressed
during \
this calculation.

Then it attempts to draw a box, but inside the box is the message:

PostScript Graphics
The PostScript text in this cell did not contains any drawing commands,
or
contained an error before the first valid drawing command.

An attempt to past the box directly onto this email yields commands:

 From In[59]:=
GraphicsData["PostScript", "\<\
%!
%%Creator: Mathematica
%%AspectRatio: .61803
MathPictureStart
/Mabs {
Mgmatrix idtransform
Mtmatrix dtransform
} bind def
/Mabsadd { Mabs
3 -1 roll add
3 1 roll add
exch } bind def
%% Graphics
%%IncludeResource: font Courier
%%IncludeFont: Courier
/Courier findfont 10  scalefont  setfont
% Scaling calculations
0.0238095 0.952381 0.0147151 0.588604 [
[ 0 0 0 0 ]
[ 1 .61803 0 0 ]
] MathScale
% Start of Graphics
1 setlinecap
1 setlinejoin
newpath
0 0 m
1 0 L
1 .61803 L
0 .61803 L
closepath
clip
newpath
% End of Graphics
MathPictureEnd
\
\>"]

I have tried several permutations, including removing the HeadScaling
argument
(sometimes it complained about the HeadScaling), replacing Pi with
N[Pi], replacing
the left hand point of the x interval with 0.3 (sometimes it complained
about the
vector length). I've even tried a single vector with no options:

Show[Graphics[Arrow[{0, 0}, {1, 1}]]]

but this also doesn't work, giving the error message:

Graphics::gprim:   Arrow[ {0, 0},{1, 1}] was \
encountered where a Graphics primitive or directive was expected.

followed by error PostScript Graphics Box as above for GuideBook's
example.

Any help would be greatly appreciated.

Sincerely,
Joe Prusa

ps: I am running V. 4.1.5.0 on a Macintosh dual G4, OS 10.2.5, with
plenty of memory and disk
space.


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