Saturday, February 27, 2010

complex plot in sage

I've been amusing myself all day with doing some complex plotting in Sage. The default color scheme has 0=black, infinity=white, and red=real. A lot of the time, this doesn't work too well, but if you plot f/abs(f) the color will just depend on the complex argument. For example, if f = (z^5+1)/(z^5-1) we get:

Or a more baroque example, f = z*log(z)*exp((z^5+1)/(z^5-1)^(1/2)):

Sometimes the default coloring is helpful, for example when showing the essential singularity at 0 of exp(1/z):

Monday, February 8, 2010

National Merit Corporation bullies blogger

I just read an appalling story of a blogger being bullied by the National Merit Scholarship Corporation. She posted their cutoff PSAT scores for each state (I hadn't realized that they varied at all) and was threatened with legal action if she didn't take down the information.

Not surprisingly, after hearing about this someone else compiled the same information, and all the corporation has done is highlight their questionable judgement in a variety of ways.