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[?] Avoid error with NSum : it returns NSum::nsnum: Summand f[n]?

M F
Posted 6 years ago
POSTED BY: M F
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For NSum, you can use a customized method: NSum[f[n], {n, 1, 100}, Method -> "WynnEpsilon"] from this SE
POSTED BY: Shenghui Yang

I'm going to have ask the same question as Rohit. Is there a particular reason why NSum? Total[Table[]] also works. Sometimes if you error one way, finding an alternative route may just be the fastest way to resolve the problem.

In[7]:= Total[Table[f[n], {n, 1, 100}]]
Out[7]= 2.69827
POSTED BY: Isaac Sarver
Rohit Namjoshi
Rohit Namjoshi
Posted 6 years ago

Is there a reason for using NSum? Sum works

Sum[f[n], {n, 1, 100}]
(* 2.69827 *)
POSTED BY: Rohit Namjoshi

your problem is that f[17] is not numerical. The error is accurate. Type the following:

In[6]:= f[17]

Out[6]= 0.112978 Cos[2.12132 t]^2

The variable "t" is not defined so the result is an expression and not a number. NSum expects numerical results.

Regards,

Neil
POSTED BY: Neil Singer
M F
M F
Posted 6 years ago

Sorry I forgot to copy paster the line defining t.

Add t=2 before and you will have the same problem.
POSTED BY: M F
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