RE: Troubleshooting Mathematic's Help

• To: mathgroup at smc.vnet.net
• Subject: [mg72489] RE: [mg72473] Troubleshooting Mathematic's Help
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 1 Jan 2007 04:11:08 -0500 (EST)

```Steven,

That must be a very old book indeed!

There are two problem. 1) the usage of Arrow has changed and 2) you do have
to work at the Graphics level.

The solution for the first problem is to use the Help notebook for the
standard package Arrow.

The plot could be written

X = {3, 4};
Show[
Graphics[
{Blue,
Arrow[{0, 0}, {0, 0} + X]}],
Axes -> True,
PlotRange -> All,
AxesLabel -> {"x", "y"},
AxesOrigin -> {0, 0}];

The question illustrates the problem with Mathematica graphics, which is a
mixture of 'set-piece' plots and graphics primitives. To combine various
graphical elements one has to keep switching beween graphical levels and
know what things go at which levels. The experts may learn how to get good
at this, but it is still a barrier to many users and even a psychological
barrier to advanced users. It is much better to keep everything at the level
of graphics primitives and graphics directives and just combine the elements
one wants one after the other.
That's what DrawGraphics does. Here is the same graphic with DrawGraphics
with the arrow connecting two points on a Sin curve.

Needs["DrawGraphics`DrawingMaster`"]

Draw2D[
{Blue,
Arrow[{0, 0}, {0, 0} + X],
Black,
Draw[4 Sin[x Pi/6], {x, 0, 3}]},
Axes -> True,
PlotRange -> All,
AxesLabel -> {"x", "y"}];

You can also do this using DisplayTogether by switching levels.

Needs["Graphics`Graphics`"]

DisplayTogether[
Graphics[{Blue,
Arrow[{0, 0}, {0, 0} + X],
Black}],
Plot[4Sin[x Pi/6], {x, 0, 3}],
Axes -> True,
PlotRange -> All,
AxesLabel -> {"x", "y"}];

David Park

From: Steven Shippee [mailto:slshippee at comcast.net]

In an old, old book by Bill Davis, Horacio Porta, & Jerry Uhl I saw an
example of how to draw a vector, e.g.,

<< Graphics`Arrow`

X = {3, 4};
Show[Arrow[X, Tail -> {0, 0}, Blue],
Axes -> True,
PlotRange -> All,
AxesLabel -> {"x", "y"},
AxesOrigin -> {0, 0}];

Not being that familiar with Mathematica, where would be the best place to
start to debug this?  Error message indicates it could be a problem with
Tail and/or with Arrow, looking at master index Arrow looks OK, unless it
needs to be embedded within the Graphics command?  Thanks in advance,

Steven Shippee

slshippee at comcast.net

```

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