## 11843 Reputation

7 years, 185 days

## Sums of certain series and a bug...

Maple

This question is related to the recent post
http://www.mapleprimes.com/questions/211460-Series-Of-Bessel-Functions

1. Consider the following fast convergent series:

f:=n->(-1)^(n+1)*1/(n+exp(n));
S1:=Sum(f(n),n=1..infinity);
evalf(S1);
S2:=Sum(f(2*n-1)+f(2*n),n=1..infinity);
evalf(S2);

As expected, the sum of the series is obtained very fast (with any precision), same results for S1 and S2.

2. Now change the series to a very slowly convergent one:

f:=n->(-1)^(n+1)/sqrt(n+sqrt(n));

evalf(S1) is computed also extremely fast, because the acceleration algorithm works here perfectly.
But evalf(S2) demonstrates a bug:

Error, (in evalf/Sum1) invalid input: `evalf/Sum/infinite` expects its 2nd argument, ix, to be of type name, but received ...

3. Let us take another series:

f:=n->(-1)^(n+1)/sqrt(n+sqrt(n)*sin(n));

Now evalf(S1) does not evaluate numerically and evalf(S2) ==> same error.
Note that I do not know whether this series is convergent or not, but the same thing happens for the obviously convergent series

f:=n->(-1)^(n+1)/sqrt(n^(11/5)+n^2*sin(n));

(because it converges slowly (but absolutely) and the acceleration fails).
I would be interested to know a method to approximate (in Maple) the sum of such series.

Edit. Now I know that the mentioned series

converges (but note that Leibniz' test cannot be used).

Maple 2016

I have posted long time ago a patch for Shadebetween and you have transformed it into a hot fix:

In the last Maple 2015 update, the problem was not fixed.

Just curious: is it fixed in Maple 2016? Because I feel that the Maplesoft team is not "impressed" by such patches.

Edit. This was a comment related to acer's patch for NLPSolve, but it was transformed (I don't know why) into a separate question.

## SEEMOUS 2016 integral...

Maple

The following integral appears in the recent SEEMOUS 2016 competition:
Int( arctan(x) * ln(1+1/x^2), x = 0..infinity );

Maple 2015 can compute it, but with a little help.

## Opening mpl/txt files...

Maple

I have a .mpl file containing some procedures and other code.
When I open the file, everything is placed in a single execution group
(I use 1D math, worksheet mode).

Is it possible to have distinct execution groups?
For example, after each two blank lines (or other separator) in the .mpl file.

The same question when using .txt files as Maple input (in this case the code being not executed).

Thank you.

## A difficult multiple integral...

Maple

Compute the following multiple integral exactly and/or with 10 correct significant digits

Int(  exp( - add(x[i],i=1..10)^3),  seq(x[i]=0..1, i=1..10) );

The problem is suggested by a previous post.

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