FUNCTION :  jcombobase - q-base of a sum of jacprods
                
jcombobase(jcombo)                                   
   jcombo is a sum of jacprods. 
   jacbase of each term is computed and the common lcm     
   is returned.    

CALLING SEQUENCE :  jcombobase(jcombo)
                    
PARAMETERS :      jcombo - sum of jacprods                            

SYNOPSIS :   
   jacbase of each term is computed and the common lcm     
   is returned.  This means that the sum
   can be rewritten in terms ofJAC(b,a) where a is the q-base.

EXAMPLES :   
> with(qseries):
> with(thetaids):

> jcombobase();
-------------------------------------------------------------
jcombobase(jcombo)                                   
   jcombo is a sum of jacprods. 
   jacbase of each term is computed and the common lcm     
   is returned.             
-------------------------------------------------------------

> jcomb:= q^(1/5)*JAC(1,5,infinity)/JAC(2,5,infinity) + 
          q^(2/5)*JAC(2,10,infinity)/JAC(4,10,infinity);
                   1/5                        2/5
                  q    JAC(1, 5, infinity)   q    JAC(2, 10, infinity)
         jcomb := ------------------------ + -------------------------
                    JAC(2, 5, infinity)        JAC(4, 10, infinity)

> jac2getacombo(jcomb);                                                        
                       eta[1, 5](tau)   eta[2, 10](tau)
                       -------------- + ---------------
                       eta[2, 5](tau)   eta[4, 10](tau)

> jcombobase(jcomb); 
                                      10


DISCUSSION :
  This means the given sum of jac prods can be written in terms of JAC(b,10).

SEE ALSO :  jacbase