realRegions -- computes the number of regions a hyperplane arrangement divides the space into

• Usage:

  b = realRegions(A, R)

• Inputs:
  • A, a list, of polynomials defining the hyperplanes
  • R, a ring,
• Outputs:
  • b, an integer, the number of regions

i1 : R = RR[x,y];

i2 : A = {x+y,x,x-y,y+1};

i3 : realRegions(A, R)

o3 = 10