addRoots(RootSystem,Root,Root) -- the sum of two roots

Synopsis

• Function: addRoots

• Usage:

  r1 + r2

• Inputs:
  • R, an instance of the type RootSystem,
  • r1, an instance of the type Root,
  • r2, an instance of the type Root,
• Outputs:
  • an instance of the type Weight, the sum of r1 and r2. Actually, it is returned as an object of class Root if the resulting weight is a root.

Description

i1 : R=rootSystemA(2)

o1 = RootSystem{...8...}

o1 : RootSystem

i2 : r1=simpleRoot(R,1)

o2 = |  2 |
     | -1 |

       2
o2 : ZZ

i3 : r2=simpleRoot(R,2)

o3 = | -1 |
     |  2 |

       2
o3 : ZZ

i4 : r=addRoots(R,r1,r2)

o4 = | 1 |
     | 1 |

       2
o4 : ZZ

i5 : addRoots(R,r1,r)

o5 = | 3 |
     | 0 |

       2
o5 : ZZ