email@example.com schrieb: > > Hmmm! Tried following this approach, i.e. solving f(b)=0 with Netwon's > and then plugging b in a=g(b), but it doesn't work. The solution > doesn't satisfy the initial system. Try for example > > L=-1 > U=1 > p=0.0013498980316301 > > I get > > a=-1 > b=1 > > which clearly is wrong, i.e., a and b don't solve the initial system, > even though f(b)=f(1)=0 and a=g(b)=g(1)=-1. I rewrite the initial > system here: > > ((a-L)^2/a)*(2/(a+b))-p=0 > ((b-U)^2/b)*(2/(a+b))-p=0 > > Am I doing something wrong, or is FriCAS/Derive solution wrong?
Here are two cases solved numerically on Derive 6.10. I am employing NSOLUTIONS rather than SOLUTIONS to avoid the solution of the quartic in terms of radicals. Because the solutions are very close-spaced here, I calculate with 50 decimal digits, but display only 20.