Homework Problem 8, Due Wednesday February 18.
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(a) Write and test a function to simulate a random 
two-dimensional vector variable  (X,Y)  with joint density

f(x,y)  =  (1.5/x^2) * (1/max(x^2, y^2)) ,  for    x, y > 1,  

(b) Same question as (a), with joint density 

g(x,y)  = c / ( 1 + (x^2+y^2)^2 ) ,  for  all real x,y

where  c  is a constant which makes  g  integrate to 1.

HINT: in (b), it simplifies matters to transform first to 
polar coordinates !

In both parts, your testing can be in terms of histograms 
versus (marginal) densities, theoretical versus simulated 
probabilities,  and/or theoretical versus empirical marginal
distribution functions.