Generating random -1 and +1 values in Excel

Question

The Rand() function would generate a real number between 0 and 1. The Randbetween(-1,1) would generate either -1, 0, or 1. What I want is only -1 or 1. And what about real numbers between -1 and 1?

Answer 1

Easy:

=IF(RAND()<0.5,-1,1)

To get the real numbers, use

=RAND()*2-1

Answer 2

Here is a solution:

=Randbetween(0,1)*2-1