When I updated to the newest version, I was unable to use the calc der feature
now it just shows d/dx without solving it

I'm doing the exact same thing as I did with the old version,
typing the equation, then selecting x, go to calc, differentiate

Am I doing something wrong -.-, or did it change in the new version?

Tested it on my laptop, pc, and phone, all had the same problem

Thanks

Do not understand, sorry

What do you mean by "calc"?

Choose the "Derivative" operator from the "Functions" pallete. In the version 0.87 just start typing "di" and you will have a list (Dynamic assistance feature). Choose "diff(2)" for derivative (with arrow down and CTRL+ENTER, SHIFT+ENTER or double click with the mouse), and you will get the same derivative template. Just fill the placeholders and pres CTRL+. for symbolic or = for numeric result.
[MATH]diff((2*x^2);x)—4*x[/MATH]
[MATH]x←5[/MATH]
[MATH]diff((2*x^2);x)=20[/MATH]

EDIT: I understand now, sorry again.
You just type
[MATH]2*x^2[/MATH]
Select the "x" and choose "Calculation->Differentiate". Then you will get the same like on your picture
[MATH]diff(2*x^2;x)[/MATH]
The first derivation over "x" is not calculated?. It is the same in this and few previous versions I tried, except in the version 0.85_3531 - it is working well (the calculation is performed). Therefore, it might be a bug? On the other hand there might be some more bugs. This is from 0.85_3531.
When I type
[MATH]4*x^3+5*x[/MATH]
And choose "Calculation->Differentiate", here is the result
[MATH]5+4*x^2+8*x^2[/MATH]
Then selecting this and choosing "Calculation->Simplify" will get this
[MATH]5+12*x^2[/MATH]
In spite of,
[MATH]diff((4*x^3+5*x);x)—5+12*x^2[/MATH]

Regards,
Radovan

Actually, I was informed about this issue couple of days before and I've fixed it already. Please, wait for next version of SMath Studio (maybe current month).

First, I really enjoy and appreciate SMath Studio. I used to use Mathcad, but I really like your program a lot. Thanks so much for making it and sharing it with everyone!

Second, I wonder if perhaps I've run into the same bug? I defined a function as follows: f(q):= 75*q - 5/4*q^2. Then I asked for the derivative and the result the software gave me was: (4*(300 - 5*q) - 20*q) / 16. That's just plain wacky. Here's a screen capture to make it more clear:

Differentiation Error?

Does that seem as wrong to you as it does to me? Thanks in advance.

Hello,

That is due to the symbolic engine of SMath. I do not know what is "under the hood" but the result is correct:
[MATH=eng]{4*(300-5*q)-20*q}/16[/MATH]
which equals to:
[MATH=eng]4*300/16=75[/MATH]+
[MATH=eng]{4*(-5*q)-20*q}/16—-{5*q}/2[/MATH]
that is
[MATH=eng]75-5/2*q[/MATH]

Symbolic manipulation of expressions is not quite available.

Regards,
Radovan

Ah, nuts. At first I did expect it to be in simplest form, but apparently I made an error in the simplification. Thanks for the correction.

Wrote

Ah, nuts. At first I did expect it to be in simplest form, but apparently I made an error in the simplification. Thanks for the correction.

You are welcome. As far as I know, SMath has its own symbolic engine (Andrey would explain that better). For some time there is Xcas functionality available on portable systems in the form of plugin. I hoped that the same would be for the desktop systems as well. I think this would improve symbolic engine of SMath quite a lot. I realy do not know what hapened with it. I even do not know if this is still actual or not.

Regards,
Radovan