FUNCTION :  qseries[theta2] - the theta function  theta (q)
                                                       2
CALLING SEQUENCE :  theta2(q,T)       
    
PARAMETERS :   q   - variable 
               T   - positive integer 
   
SYNOPSIS :   
                                                        T 
 theta2(q,t) returns the q-series expansion to order O(q ) of 

                                  oo
                                 -----           2
                                  \       (n+1/2)
              theta (q)   =        )     q
                   2              /
                                 -----
                                n = - oo

EXAMPLES :   
   
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> theta2(q,50);                             

    72      56      42      30      20      12      6      2        90   1/4
(2 q   + 2 q   + 2 q   + 2 q   + 2 q   + 2 q   + 2 q  + 2 q  + 2 + q  ) q

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SEE ALSO :   jacprod, tripleprod, theta, theta3, theta4