show1         demonstrates convolution of 1000 times (0.9,0.1)
show2         convolves 1000 times a silly distbn


doit0   is (0.9,1) (switches over after 100 to fast mode) (goes to 2500)

doit           is a similar crazy distbn, and switches to automode
		after a few hundred.  

doit2 does it on logscale

doit3 shows real scale and logscale on one plot