"Testing denominator"

clear

T = denominator(2/3)
check(T = 3) 
T = denominator(x)
check(T = 1) 
T = denominator(1/x)
check(T = x) 
T = denominator(a+b)
check(T = 1) 
T = denominator(1/a+1/b)
check(T = a*b) 
T = denominator(1/(x-1)/(x-2))
check(T = x^2-3*x+2)
