Basic introduction to Emacs Calc
C-x * c - To start Calc
4 WAYS TO PERFORM CALCULATIONS
Reverse Polish Notation (RPN) is a way of writing mathematical expressions that uses a stack to store numbers. In RPN, you enter the operands (value) first, then the operator (the symbol that performs an operation). For example, to add 2 and 3, you would enter 2, 3, and then +. Calc is a calculator that supports RPN.
DEL is used to clear/erase the result
Type 2 RET 3 + Q to compute the square root of 2+3, which is 2.2360679775
Type P 2 ^ to compute the value of ‘pi’ squared, 9.86960440109
Type TAB to exchange the order of these two results
Algebraic calculation. You can also enter calculations using conventional “algebraic” notation. To enter an algebraic formula, use the apostrophe key (')
Type ' sqrt(2+3) RET to compute the square root of 2+3
One can have algebraic mode by invoking m a
Note that if the formula begins with a function name (such as sqrt), you need to use the apostrophe even if you are in Algebraic mode.
Calc gives ‘/’ lower precedence than ‘*’, so that ‘a/b*c’ is interpreted as ‘a/(b*c)’
In an algebraic formula, $ represents the number on the top of the stack
The notations \[, \]$, and so on stand for higher stack entries
Keypad mode. If you are using the X window system, press C-x * k to get Keypad mode. (If you don’t use X, skip to the next section.)
Grabbing data.
15450
24563
18338
C-x * g. Then type V R + to add the numbers
Also a special grab-and-sum-columns command, C-x * :
Type d B to view the solutions in more readable notation
You don’t really need the second RET in 2 RET 3 RET +. 2 RET 3 + will work just as well.
To clear the stack: M-0 DEL
To exit C-x * is the same command as to start C-x *
U is undo (shift-u)
D is redo
You can think of undo and redo as a sort of “time machine.” Press U to go backward in time, D to go forward.
The trail records everything we have recorded since we loaded the Calculator t d
To navigate the trail:
t ] Go to the trail
t p Move to the previous item
t n Move to the next item
t y yank number back to the stack
t r trail search reverse
you can now press C-s or C-r to continue the search forwards or backwards as you like
to finish the search press RET and t y
C-g cancels