posxinphb

  
Purpose 		
 
Return the position of the Lie bracket $x$ in the basis $B$.





Syntax 		 
p:=posxinphb(x,B);




Description 		 

The command posxinphb, returns the position of $x$ within
the PHB, if it exists otherwise returns $-1$. It is assumed that $x$
is a , i.e. the scalar parts have been removed (see
function simpLB below which allows to obtain the pure bracket).





Arguments 		 
$x$  Some pure Lie bracket.


 		 $B$ $\parbox{0.64\textwidth}{Philip Hall basis}$




Examples 		 

Consider the PHB $B$, given in example for the function  phb in
p. .  Then
> p:=posxinphb(f1~ &* (f1~ &* (f0~ &* f1~)),B);
p:=22





Notes 		 

This function is required by the phbize routine. It has been
provided to the user for his/her convenience, however it is unlikely that it
will really be needed.