12 misc== 
 * p 156: Leibnz series is most famouse inf series for pi, but converges very slowly, hence never used. 
 * p 160-161:  the first two infinite expressiosn for pi were inf products, not sums!  First in 1593 by Francois Veite; 2nd by  John Wallis in 1655.  
 * p 161:  in 1999  Thomas Osler demonstrated that those two products are closely related 

 == 13 History== 

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