Re: plot error messages are completelly missing
- To: mathgroup at smc.vnet.net
- Subject: [mg81004] Re: plot error messages are completelly missing
- From: Szabolcs <szhorvat at gmail.com>
- Date: Fri, 7 Sep 2007 02:12:43 -0400 (EDT)
- Organization: University of Bergen
- References: <fbojp5$jbs$1@smc.vnet.net>
Josef Otta wrote:
> Hi all,
>
> I have a question to a catching error messages is the evaluation of
> graphics functions in the version 6. For example, consider a function
> plotting with non real values:
>
> {Plot[Sqrt[x], {x, -2, 1}],
> $MessageList}
>
> in version 5.2 the output is a plot with these messages
>
> {Plot::plnr, Plot::plnr, Plot::plnr, General::stop}}
>
> If I use the same approach in the version 6.0 i get no error messages
> and that is a big problem for me. Do you have any idea how to get
> these errors?
> I do not know how to get these messages also in the cases where
>
> Complex, ComplexInfinity, Indeterminate, Null, Underflow or Overflow
>
> occur in the evaluation of almost every graphics function.
I would like to know this too. On[General::plnr] turns on this warning
message. However, the message is only issued when Plot encounters a
symbolic expression. It does not work for complex numbers, infinity etc.
And I do not understand why this new General::plnr is turned off by
default. Passing a completely non-numerical argument (as opposed to a
function that evaluates to complexes in some regions) to Plot is an
unintentional mistake in 99% of the cases. The only time I turned off
Plot::plnr in 5.2 was when repeatedly plotting things like Plot[Sqrt[x],
{x, -1, 1}], but these kinds of examples do not warn with Plot::plnr any
more in Mathematica 6 (even though it would often be useful).
Szabolcs