I've noticed an f(x) button in calculator's (gcalctool) advanced mode. The button opens a drop-down list with some predefined functions. Is it possible to define more?
If you press F1 and read the help page about functions it says: “GCalctool does not support user-defined functions.”, so I guess the answer is no.
Of course you can propose additions to the program's developer(s) or write your own patch to add more functions.
I don't see an f(x) button, but in scientific mode there is a 'Fun' button with a drop down list. Initially this is empty except for an 'Edit Functions...' button. If you click this, you can edit the functions 0 to 9.
If you do something like this:
selecting F0 from the function list will add2 to your answer. For more details, see the Gcalctool help:
There doesn't seem to be a way to define a function in the traditional sense (where you define f(x) to be a transformation of x into another value)
Nope, but you can install Qalculate, it's a nice calculator with a lot of options and functions.
Here a screencapture.