>=

[procedure] = z1 z2 ...

[procedure] < x1 x2 ...

[procedure] <= x1 x2 ...

[procedure] > x1 x2 ...

[procedure] >= x1 x2 ...

R5RS, R6RS

In R6RS:

   (= +inf.0 +inf.0) => #t
   (= -inf.0 +inf.0) => #f
   (= -inf.0 -inf.0) => #t

 When (finite? x) => #t, 
   (< -inf.0 x +inf.0) => #t 
   (> +inf.0 x -inf.0) => #t 

 When (number? z) => #t,
   (= +nan.0 z) => #f
   (> +nan.0 z) => #f
   (< +nan.0 z) => #f