func removeExactEdges(n *coupling.Node, exact [][]bool) {
n.Visited = true
for _, row := range n.Adj {
for _, edge := range row {
// if the edge node adj matrix is nill, we do not have to recursivevly call it,
// and just just delete n from its successor slice
if edge.To.Adj == nil {
coupling.DeleteNodeInSlice(n, &edge.To.Succ)
continue
}
// if the edge has already been visited, we do not have have to recursively call
if edge.To.Visited {
coupling.DeleteNodeInSlice(n, &edge.To.Succ)
continue
}
// recursively removes edges and successor node bottom up
removeExactEdges(edge.To, exact)
coupling.DeleteNodeInSlice(n, &edge.To.Succ)
}
}
// here we do the actual removing of edges
exact[n.S][n.T] = true
exact[n.T][n.S] = true
n.Adj = nil
n.Visited = false
return
}
func preparenode() coupling.Node {
var n coupling.Node
e1 := coupling.Edge{&coupling.Node{S: 0, T: 0}, 0.1, true}
e2 := coupling.Edge{&coupling.Node{S: 0, T: 1}, 0.5, true}
e3 := coupling.Edge{&coupling.Node{S: 1, T: 0}, 0, false}
e4 := coupling.Edge{&coupling.Node{S: 1, T: 1}, 0.4, true}
n.Adj = [][]*coupling.Edge{
[]*coupling.Edge{&e1, &e2},
[]*coupling.Edge{&e3, &e4}}
return n
}
func findReverseReachable(node *coupling.Node, reachables []*coupling.Node) []*coupling.Node {
node.Visited = true
for _, succ := range node.Succ {
if !coupling.IsNodeInSlice(succ, reachables) {
reachables = append(reachables, succ)
}
if len(succ.Succ) == 0 || succ.Visited {
continue
}
reachables = findReverseReachable(succ, reachables)
}
node.Visited = false
return reachables
}
func setUpCoupling() coupling.Coupling {
c := coupling.New()
n1 := coupling.Node{S: 0, T: 0}
n2 := coupling.Node{S: 0, T: 1}
n3 := coupling.Node{S: 1, T: 0}
n4 := coupling.Node{S: 1, T: 1}
e1 := coupling.Edge{&n1, 0.5, true}
e2 := coupling.Edge{&n2, 0.2, true}
e3 := coupling.Edge{&n3, 0, false}
e4 := coupling.Edge{&n4, 0.3, true}
n1.Succ = []*coupling.Node{&n1, &n2, &n4}
n2.Succ = []*coupling.Node{&n2, &n4, &n1}
n4.Succ = []*coupling.Node{&n2, &n1, &n4}
n2.Adj = [][]*coupling.Edge{[]*coupling.Edge{&e1, &e2}, []*coupling.Edge{&e3, &e4}}
c.Nodes = []*coupling.Node{&n1, &n2, &n3, &n4}
return c
}
func setUpLinearEquations(n *coupling.Node, exact [][]bool, d [][]float64, a *[][]float64, b *[]float64, i int, index *[]*coupling.Node, lambda float64) {
n.Visited = true
for _, row := range n.Adj {
for _, edge := range row {
// if the node is non-basic, we do not have to look at it
if !edge.Basic {
continue
}
// if the node is exact, we add its probablity times its distance to the i'th row in the b vector
if exact[edge.To.S][edge.To.T] {
(*b)[i] += d[edge.To.S][edge.To.T] * edge.Prob * lambda
continue
}
// if the node has already been visited, we do not have to add it as a new linear equation
// and subtract its probability from its corresponding place in the a matrix
if edge.To.Visited {
rowindex := findRowIndex(index, edge.To)
(*a)[i][rowindex] -= edge.Prob * lambda
continue
}
// we have to add a new linear equation, so we update a, b, and index
addLinearEquation(a, b, index, edge.To)
(*a)[i][len(*a)-1] -= edge.Prob * lambda
// recursively sets up the linear equation
setUpLinearEquations(edge.To, exact, d, a, b, len(*a)-1, index, lambda)
}
}
return
}