Monday, 20 June 2016

calculus - Could 4+2+4+2+4+2+cdots=1?

In physics classes, on this StackExchange and even in blogs the sum 1+2+3+4+=112 has been under the microscope.





As a consequence of the trapezoid rule, the error to the Riemann sum is bounded by the second derivative.




N0f(x)dx=12f(0)+f(1)++f(N1)+12f(N)+O(Nf˙C2)



Letting f(x)=(1x/N)+ we get N1i=01=12+N01dx+O(1).



I am wondering what happen if we use the Simpson rule:



N0f(x)dx=13(f(0)+4f(1)+2f(2)++4f(N1)+f(N))+O(N||f||˙C4)



Now we plug in f(x)=(1x)+ and get




13(4+2+4+2+)=13+N0f(x)dx+O(N3)



Is that still consistent with the other types of sums you get from Euler-Macularin type summation methods?

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