Multifractals

β(q) is a decreasing function of q

Differentiating
piqriβ(q) = 1
with respect to q gives
piqriβ(q)(ln(pi) + ln(ri) dβ/dq) = 0
Solving for dβ/dq,
dβ/dq = -( piqriβ(q)(ln(pi)))/( piqriβ(q)(ln(ri)))
Because each piq > 0, riβ(q) > 0, ln(pi) < 0, and ln(ri) < 0, we see dβ/dq < 0.
When all ri take on a common value r, this formula leads to a simple expression for alpha:
alpha = -dβ/dq = ( piq ln(pi))/(ln(r) piq)

Return to the range of alpha values.