missing buttons: pi, arcsin, arccos, arctan, arsinh,...

Thank you for your bug report and taking the time to make Ubuntu better.

I do actually think everything you need is already there: For converting degrees to radians you can use the general conversion mechanism present in the "advanced" mode -- In the box in the type left chose "Angles" -> "degrees" and in the one on the right chose "radians".
Pi is also there, try the "π" button (also in "advanced" mode, above "=") or use Ctrl+P
For arctan: The documentation says you can use "atan" but that apparently does not work. What does work however is using tan-¹ by typing "tan" and then pressing Ctrl+I for inversion.

I've mark the bug as invalid, please feel free to reopen it if you still think it should be filed as a bug.

Thanks for your answer.

You are right, the π is there. I think I couldn't find it because in the default font, it looks like a box with the bottom part removed. Usually, it is typeset more curvy.

Thanks for the hint with Ctrl+I, it works well. However, it is a hidden feature and I think it is not accessible enough. There should be a non-shortcut way to activate this function. Either a menu item or a button "^-1". The easiest solution would be to add arcsin, ... to the list of extra functions under the "f(x)" button in advanced mode (possibly in a submenu "trigonometry").

This is the default calculator in Ubuntu, so on a fresh system, I would like it to "just work", i. e. it should be intuitive and there should be no need to read the documentation first. (Although this is never a bad idea.)

Allowing arcsin to be entered manually would be nice as well. Personally I prefer plain text input over some advanced formatting and UTF-8 characters like √ and ×. (But it seems to be done well, I can copy & past without problems.)

I'd like to add, that sin⁻¹(x) is not a very nice notation because it conflicts with sin²(x) witch, I think, is much more common.

> Thanks for the hint with Ctrl+I, it works well. However, it is a hidden
> feature and I think it is not accessible enough. There should be a non-
> shortcut way to activate this function. Either a menu item or a button
> "^-1".
Well, there is a "x-¹" button which does the same as Ctrl+I…

> Allowing arcsin to be entered manually would be nice as well.
Yes, I agree. As I said before, the documentation says that it is
possible to enter "asin" which does however not work. So what about
making the report specifically about this issue (and suggest arcsin
instead of/in addition to "asin" which is more a programming language
name)?

> I'd like to add, that sin⁻¹(x) is not a very nice notation because it
> conflicts with sin²(x) witch, I think, is much more common.
Actually I do think it is ok as it is, IMO most people will read
sin⁻¹(x) as arcsin and sin²(x) as the square of the function value --
to me the latter always felt "more wrong" (why not just write sin(x)²
?).

> Well, there is a "x-¹" button which does the same as Ctrl+I…

See, this button is very misleading. I never thought, that "x" could also stand for a function and not only for a number. You have one button that does completely different things.

2⁻¹ => 0.5
sin⁻¹0.5 => 30
sin²30 => 0.25
and:
sin⁻²0.5 => 900

The last one is very questionable, there are only 2 possible interpretations for sin⁻²0.5: Either 1/(sin²0.5) or arcsin(arcsin(0.5)), but not a mixture of both concepts (multiplicative inverse and compositional inverse).

>> Allowing arcsin to be entered manually would be nice as well.
> Yes, I agree. As I said before, the documentation says that it is
> possible to enter "asin" which does however not work. So what about
> making the report specifically about this issue (and suggest arcsin
> instead of/in addition to "asin" which is more a programming language
> name)?

Ok, sounds good.

>> I'd like to add, that sin⁻¹(x) is not a very nice notation because it
>> conflicts with sin²(x) witch, I think, is much more common.
> Actually I do think it is ok as it is, IMO most people will read
> sin⁻¹(x) as arcsin and sin²(x) as the square of the function value --

I agree, that most people would recognize it correctly. It's just strange to use both conflicting styles at the same time.

> to me the latter always felt "more wrong" (why not just write sin(x)²
> ?).

If you write sin λ without the parentheses, sin λ² would too much look like sin(λ²).

Thank you for your bug report. The issue is an upstream one and it would be nice if somebody having it could send the bug the to the people writting the software (https://wiki.ubuntu.com/Bugs/Upstream/GNOME)