realrank(...,Range=>...) -- can be assigned an interval

• Usage:

  realrank(F,Range=>(a,b))

  realrank(F,Range=>[a,b])

• Inputs:
  • F, a ring element, a binary form $F_u(x,y)\in \mathbb{Q}[u][x,y]$
  • a, a rational number, or an InfiniteNumber
  • b, a rational number, or an InfiniteNumber
• Outputs:
  • r, an integer, if the real rank of $F_u(x,y)$ is $r$ for all the values $u\in(a,b)$ or $u\in[a,b]$