Is there a program or a key map that allows me to easily type mathematcial symbols and unicode letters such as these symbols in a web form?
Maybe a keyboard mapping? An assitant program?
Several years ago, I configured a macro/hotkey program for exactly this purpose. I set up a bunch of keyboard combos as triggers with corresponding paste-character events. That way, I can for example, press Ctrl+Alt+M to enter a
μ or Win+Space to enter a non-breaking-space.
I have well over 100 of these to simplify entering all kinds of extended characters and have become quiet dependent on them (I don't even remember the character-codes of most of them).
There are countless programs that you can use for this purpose, but a simple option is to use AutoHotKey. The beauty of AHK is that it fully supports Unicode characters (at least for this purpose) unlike a lot of the older (and even newer?) hotkey/macro programs. It is also easier to edit since it is a simple text file (though you can compile the result to be an executable to auto-run in the background). The only thing to note is that you must set the script file to use UTF-8 encoding instead of ANSI if you want Unicode characters to work in addition to just extended characters (#128-255).
Here is a small script to get you started:
!= ::Send ≠ ; Alt + = = not-equals (this one just sounds weird)
#X ::Send Ξ ; Win + X = capital Xi
^+1 ::Send ¡ ; Ctrl + Shift + 1 = inverted exclamation mark
^+4 ::Send ¢ ; Ctrl + Shift + 4 = cent symbol
#/ ::Send ‽ ; Win + / = interrobang
#T ::Send 树 ; Win + T = Chinese character for tree
You can set the keys and their modifiers as desired and only have to copy-paste the characters one final time.