#1083 Taylor polynomials of polylogs

None
closed
nobody
5
2013-01-02
2007-01-22
No

(%i4) taylor(li[7](x),x,0,4);
`taylor' encountered an unfamiliar singularity in:

A correct answer is

x + ((x^2)/128) + ((x^3)/2187) + ((x^4)/16384) + . . .

An easy fix is to append a deftaylor for li. But
deftaylor has its own problems:

(%i1) deftaylor(li[s](x), sum(x^k/k^s,k,1,inf))$
(%i2) taylor(li[3](x),x,0,2);
(%o2) x+x^2/8+...
(%i3) taylor(li[3](x),x,1,2);
`taylor' unable to expand at a point specified in:
sum(x^*index/*index^s,*index,1,inf)

Discussion

  • Dan Gildea

    Dan Gildea - 2013-01-02
    • status: open --> closed
    • milestone: --> None
     
  • Dan Gildea

    Dan Gildea - 2013-01-02

    Works since commit
    5d98db3eb50264d7b3a436a61b24262b47890942

     

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