Generate random numbers with fixed sum constraint

Hi, I am trying to generate random numbers from a uniform distribution subject to the following constraints

a+b*x+c*(x^2)+d*y+e*(y^2)+f*x*y = 1 when x = 7 and y = 29.4 where {a,b,c,d,e,f} are random variables sampled from a uniform distribution each with a different upper and lower bound. How can I do this.

I came across a somewhat similar question at http://www.mathworks.com/matlabcentral/fileexchange/9700-random-vectors-with-fixed-sum. but am not sure how to apply it to my problem.

Any suggestions?

Answer 1

[Adrian]

Any ideas???