codeCBHcf

  
Purpose 		 

Generate code in C or Fortran for the scalar coefficients of some 
Lie expression in terms of Lie products (not necessarily in a PHB).





Syntax 		
e:=codeCBHcf(expr,B,language);




Description 		 

Generates code in C or Fortran for the scalar coefficients of some 
Lie expression in terms of Lie products (not necessarily in a PHB). 





Arguments 		 
 $expr$  $\parbox{0.64\textwidth}{A Lie algebra generator, 
 bracket or Lie polynomial.}$


 		 $B$ A  Philip Hall basis or an empty list.


 		 $language$ Either of the strings C or fortran.




Examples 		 

Consider the P. Hall basis B, of example for the function phb on page , and the Lie polynomial zr given in the example for the function reduceLB on page .  Then, the expressions in the C language for the scalar coefficients of a given Lie polynomial, for example, given by the first and third terms in zr can be obtained as:  
> codeCBHcf(op(1,zr)+op(3,zr)*epsilon,z,C);
1.  B[12] = `&*`(f2,`&*`(f0,f1))
      t0 = -u2_2*u0_1*u1_2/12.0+u0_1*u2_1*u1_2/12.0
           -u2_1*u1_1*u0_2/12.0+u0_2*u1_1~*u2_2/12.0;
2.  B[6] = `&*`(f1,f2)
      t0 = (-u2_1*u1_2+u1_1*u2_2)*epsilon/2.0;

Providing a P. Hall basis is not essential, however a list or set containing at least one element must be given instead, as shown by the next example.
> codeCBHcf(op(1,z6r)+op(3,z6r)*epsilon,[[]],fortran);
1.  B[-1] = []
      t0 = -u2_2*u0_1*u1_2/12+u0_1*u2_1*u1_2/12
     #-u2_1*u1_1*u0_2/12+u0_2*u1_1*u2_2/12
2.  B[-1] = []
      t0 = (-u2_1*u1_2+u1_1*u2_2)*epsilon/2

Note above that the element which would correspond to a P. Hall basis is simply a list containing an empty list, [[]], but could have been also [``], or any other list containing one element, but never an empty expression, such as [].