treetime/merger_models.py
def cost(self, t_node, branch_length, multiplicity=2.0):
        '''
        returns the cost associated with a branch starting at t_node
        t_node is time before present, the branch goes back in time

        Args:
            - t_node:           time of the node
            - branch_length:    branch length, determines when this branch merges with sister
            - multiplicity:     2 if merger is binary, higher if this is a polytomy
        '''
        merger_time = t_node+branch_length
        return self.integral_merger_rate(merger_time) - self.integral_merger_rate(t_node)\
                 - np.log(self.total_merger_rate(merger_time))*(multiplicity-1.0)/multiplicity
def cost(self, t_node, branch_length, multiplicity=2.0):
        '''
        returns the cost associated with a branch starting at t_node
        t_node is time before present, the branch goes back in time

        Args:
            - t_node:           time of the node
            - branch_length:    branch length, determines when this branch merges with sister
            - multiplicity:     2 if merger is binary, higher if this is a polytomy
        '''
        merger_time = t_node+branch_length
        return self.integral_merger_rate(merger_time) - self.integral_merger_rate(t_node)\
                 - np.log(self.total_merger_rate(merger_time))*(multiplicity-1.0)/multiplicity
returns the cost associated with a branch starting at t_node
        t_node is time before present, the branch goes back in time

        Args:
            - t_node:           time of the node
            - branch_length:    branch length, determines when this branch merges with sister
            - multiplicity:     2 if merger is binary, higher if this is a polytomy