>>Quite right, R is a subset of C, C is form a +/- bi where a,b are real, i=sqrt(-1), and b=0 for R (real), etc.
>
>The definition for i: i**2=-1. Because sqrt is not defined on negative numbers.
>
No argument on that. But i=sqrt(-1) is what is (at least when I taught math) commonly used as a tool to explain to 'non-math' people what the imaginary part of a non-real quadratic solution is...
The Anonymous Bureaucrat,
and frankly, quite content not to be
a member of either major US political party.