FUNCTION :  eta[etamult] - computes the etamultiplier of eta(M tau)
                           for a given M in SL[2](Z).
                

CALLING SEQUENCE :  etamult(M)
                    

PARAMETERS :      -  
                  -            

GLOBAL VARIABLES : 

SYNOPSIS :   
   

EXAMPLES :   

DISCUSSION :

SEE ALSO :