@Kitonum 

Thanks, surprisingly easy...

It is desirable to have the full list of changes/improvements in this release with demonstration of new features. For comparison, Wolfram Research describes in details each new release of its software.

Please, clarify you questions.

What do you mean under "transition matrix"?

Yes, it's possible to convert any help page into a worksheet, apply styles and build a new Help System on the base of converted sheets. Interesting workaround, but time-consuming.....

Result is the same. I'll try to reinstall later.

@Carl Love 

Maybe, my installation of Maple is corrupted?

@maple2015 

Please, go tp Tools > Options... > Precision and adjust parameter "Limit expression length to..." or uncheck it.

@tomleslie 

Thank you, this works.....

@acer 

Thank you. I'm aware of other dsolve options. In fact, I solve a multi-point BVP (not presented in the question), reduced to two-point one. Using Array is more appropritate for a number of reasons. And, at last, the question was about a way of calculation of y'' with use of values of a function and y'.

@Kitonum 

Sorry, my question was invoked by mistyping. I accidentally mixed up “numbcomp” and “numbcomb”

Глянул кратко. Не определены функции p(t), q(t), r(t)

@acer 

Than you.
Empty first line has solved the issue.

I think you missed * between D[4](a) and the following parethenses (.......)

Maple understand D[4](a) as a function and (x, y, t, u(x, y, t), diff(u(x, y, t), x), diff(u(x, ............) as arguments list.

@Daniel Skoog 

I'm aware of using maplemint through code invoking. But, as you understand, it is natural to have uniform behaviour of Startup Code Editor and Code Edit Region. I hope, embeding maplemint into Code Edit Region is a matter of the near future.

Regarding zoom, Zoom-In/Zoom-Out buttons switch zoom between predifined levels (75-100-125 ...), but Ctrl+wheel, indeed, produces  more uniform stepping.

Regards

Thank you, Daniel, for detailed description of new features.

In order to tell something definitively, it is necessary to work with new release a while.

I can share only first impressions upon it.

1. I'm indeed excited about possibilities of Context Panel. Due to it, some actions can be performed many times faster.
2. Unfortunately, as I understand, the maplemint feature is embedded only into Startup Code Editor. I suppose, it makes sense to embed it in Code Edit Region.
3. Regarding interface changes, it is pity to remark that zoom factor remains the same -- separate 75%, 100%, 125% ... values. These values originated back in 1990s when graph possibilities of software were very poor. For example, old versions of PageMaker had also discrete zoom factors. Today, there are no software or hardware related obstacles to make zoom factor continuous, as in main part of modern packages.