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Re: Additive inverses of lists?

  • To: mathgroup at
  • Subject: [mg95769] Re: Additive inverses of lists?
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at>
  • Date: Mon, 26 Jan 2009 06:50:07 -0500 (EST)
  • Organization: The Open University, Milton Keynes, UK
  • References: <glk1l9$lmj$>

In article <glk1l9$lmj$1 at>,
 Erik Max Francis <max at> wrote:

> Is this a known no-no, or did I find something new?  (I obviously 
> originally tried it in the graphical front end; I'm only doing it from 
> the command line interface for demonstration.)

This seems to be new and this also works on Windows :-)

> max@boron:~% math
> Mathematica 7.0 for Linux x86 (32-bit)
> Copyright 1988-2008 Wolfram Research, Inc.
> In[1]:= StreamPlot[-{x, y}, {x, -3, 3}, {y, -3, 3}]
> zsh: segmentation fault  math

Upon evaluation of the above line from within the front end, Visual 
Studio Just-in-Time debugger traps the following error: "An unhandled 
win32 exception occurred in MathKernel.exe [4060]"

Forcing the evaluation of the expression -{x, y} yields the expected 
behavior and plot, though.

StreamPlot[Evaluate[-{x, y}], {x, -3, 3}, {y, -3, 3}]

In[5]:= {$Version, $ReleaseNumber}

Out[5]= {"7.0 for Microsoft Windows (32-bit) (November 10, 2008)", 0}

> Interestingly enough if the StreamPlot is not involved, nothing but happens:
> In[1]:= -{a, b}
> Out[1]= {-a, -b}
> And plotting {-x, -y} instead of -{x, y} works fine:
> In[1]:= StreamPlot[{-x, -y}, {x, -3, 3}, {y, -3, 3}]
> Out[1]= -Graphics-


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