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Question: How get numerical result when evalf fails

Question:How get numerical result when evalf fails

crockeea 10
evalf summation plotting
May 27 2015
1

In the following worksheet, I can evaluate S(32), but not S(31). As a result, I can't use any value that depends on S(31) (or any i<31), for example, the graph is incomplete. How can I get Maple to evaluate S(31)?

> 

restart
> 

sigma := 167:
> 

t := proc (i) options operator, arrow; exp(-(1/2)*i^2/sigma^2) end proc:
> 

S := proc (l) options operator, arrow; 1+2*(sum(t(i), i = l .. infinity)) end proc:
> 

evalf(S(32))

356.9784188

 (1)
> 

evalf(S(31))

1.+2.*(sum(exp(-(1/55778)*i^2), i = 31 .. infinity))

 (2)

Expected result of evalf(S(31)):

> 

evalf(S(32)+2*t(31))

358.9442559

 (3)
> 

plot(S(y), y = 20 .. 50)

 
> 

``


All told, S(i) fails for i in [0..31], i = 115,116, and 221. S(i) succeeds for all other i < 3500.

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