Re: Why don't my plots appear? My 5.2 code no longer works correctly in 6.0

• To: mathgroup at smc.vnet.net
• Subject: [mg89367] Re: [mg89326] Why don't my plots appear? My 5.2 code no longer works correctly in 6.0
• From: "Charlie Brummitt" <cbrummitt at wisc.edu>
• Date: Sat, 7 Jun 2008 02:59:05 -0400 (EDT)
• References: <200806061044.GAA24071@smc.vnet.net>

```The Print command is what I need! Thanks for all the kind and helpful
replies.
-Charlie

On Fri, Jun 6, 2008 at 7:36 AM, Murray Eisenberg <murray at math.umass.edu>
wrote:

> You'll probably get zillions of responses to your question.
>
> The treatment of Plot and related functions has changed with version 6: the
> graphic created is no longer a side-effect of evaluating the function, but
> rather the actual, direct RESULT of the function.  (In Mathematica 5 and
> before, the display was a side-effect whereas the direct result was a
> -Graphics- object.)
>
> A consequence is that following a Plot with a semi-colon now has EXACTLY
> the same effect of following any other command with a semi-colon: it
> suppresses the result.  More precisely, it produces a Null result, which by
> default is not shown in any way.
>
> In general, a semi-colon is used to separate the parts of a compound
> expression, for example:
>
>  a = 2; Plot[Sin[a x], {x, 0, Pi}]; "Hello, world!"  (* NO! *)
>
> has result the string 'Hello, world!.  And indeed in Mathematica 6 you the
> semi-colon after the Plot expression appears in red to warn you.  To make
> the plot appear, use Print:
>
>  a = 2; Print[Plot[Sin[a x], {x, 0, Pi}]]; "Hello, world!"  (* Yes *)
>
> Note this has nothing to do, per se, with Modules -- just compound
> expressions in general.
>
>
>
> Charlie Brummitt wrote:
>
>> Hello,
>> I am running into difficulties with Plot. Some code of mine that worked in
>> 5.2 no longer works correctly in 6.0.2.0. Specifically, no plots appear
>> whenever Plot (or Plot3D or DensityPlot or ListPlot) is called within a
>> function that I have defined.
>>
>> Here is a closely related question: What does the red semicolon ";" mean
>> at
>> the end of "Plot[ ... ];"? Why is it red? In 5.2, placing a semicolon at
>> the
>> end of Plot[] allowed me to output a plot in the middle of a computation,
>> without halting the computation. Now I can no longer seem to output a plot
>> in the middle of a long computation. (I only see the output of Print[]
>> commands.) I must be able to see these plots during long computations,
>> like
>> I was able to in 5.2.
>>
>>
>> Thanks,
>>
>> Charlie
>>
>>
>>
> --
> Murray Eisenberg                     murray at math.umass.edu
> Mathematics & Statistics Dept.
> Lederle Graduate Research Tower      phone 413 549-1020 (H)
> University of Massachusetts                413 545-2859 (W)
> 710 North Pleasant Street            fax   413 545-1801
> Amherst, MA 01003-9305
>

```

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