Basic Commands
==============

To start the Calculator in its standard interface, type `M-x calc'.
By default this creates a pair of small windows, `*Calculator*' and
`*Calc Trail*'.  The former displays the contents of the Calculator
stack and is manipulated exclusively through Calc commands.  It is
possible (though not usually necessary) to create several Calc Mode
buffers each of which has an independent stack, undo list, and mode
settings.  There is exactly one Calc Trail buffer; it records a list
of the results of all calculations that have been done.  The Calc
Trail buffer uses a variant of Calc Mode, so Calculator commands still
work when the trail buffer's window is selected.  It is possible to
turn the trail window off, but the `*Calc Trail*' buffer itself still
exists and is updated silently.  See Trail Commands.

In most installations, the `M-# c' key sequence is a more convenient
way to start the Calculator.  Also, `M-# M-#' and `M-# #' are synonyms
for `M-# c' unless you last used Calc in its "keypad" mode.

Most Calc commands use one or two keystrokes.  Lower- and upper-case
letters are distinct.  Commands may also be entered in full `M-x'
form; for some commands this is the only form.  As a convenience, the
`x' key (`calc-execute-extended-command') is like `M-x' except that it
enters the initial string `calc-' for you.  For example, the following
key sequences are equivalent: `S', `M-x calc-sin RET', `x sin RET'.

The Calculator exists in many parts.  When you type `M-# c', the Emacs
"auto-load" mechanism will bring in only the first part, which
contains the basic arithmetic functions.  The other parts will be
auto-loaded the first time you use the more advanced commands like
trig functions or matrix operations.  This is done to improve the
response time of the Calculator in the common case when all you need
to do is a little arithmetic.  If for some reason the Calculator fails
to load an extension module automatically, you can force it to load
all the extensions by using the `M-# L' (`calc-load-everything')
command.  See Mode Settings.

If you type `M-x calc' or `M-# c' with any numeric prefix argument,
the Calculator is loaded if necessary, but it is not actually started.
If the argument is positive, the `calc-ext' extensions are also loaded
if necessary.  User-written Lisp code that wishes to make use of
Calc's arithmetic routines can use `(calc 0)' or `(calc 1)' to
auto-load the Calculator.

If you type `M-# b', then next time you use `M-# c' you will get a
Calculator that uses the full height of the Emacs screen.  When
full-screen mode is on, `M-# c' runs the `full-calc' command instead
of `calc'.  From the Unix shell you can type `emacs -f full-calc' to
start a new Emacs specifically for use as a calculator.  When Calc is
started from the Emacs command line like this, Calc's normal "quit"
commands actually quit Emacs itself.

The `M-# o' command is like `M-# c' except that the Calc window is not
actually selected.  If you are already in the Calc window, `M-# o'
switches you out of it.  (The regular Emacs `C-x o' command would also
work for this, but it has a tendency to drop you into the Calc Trail
window instead, which `M-# o' takes care not to do.)

For one quick calculation, you can type `M-# q' (`quick-calc') which
prompts you for a formula (like `2+3/4').  The result is displayed at
the bottom of the Emacs screen without ever creating any special
Calculator windows.  See Quick Calculator.

Finally, if you are using the X window system you may want to try `M-#
k' (`calc-keypad') which runs Calc with a "calculator keypad" picture
as well as a stack display.  Click on the keys with the mouse to
operate the calculator.  See Keypad Mode.

The `q' key (`calc-quit') exits Calc Mode and closes the Calculator's
window(s).  It does not delete the Calculator buffers.  If you type
`M-x calc' again, the Calculator will reappear with the contents of
the stack intact.  Typing `M-# c' or `M-# M-#' again from inside the
Calculator buffer is equivalent to executing `calc-quit'; you can
think of `M-# M-#' as toggling the Calculator on and off.

The `M-# x' command also turns the Calculator off, no matter which
user interface (standard, Keypad, or Embedded) is currently active.
It also cancels `calc-edit' mode if used from there.

The `d SPC' key sequence (`calc-refresh') redraws the contents of the
Calculator buffer from memory.  Use this if the contents of the buffer
have been damaged somehow.

The `o' key (`calc-realign') moves the cursor back to its "home"
position at the bottom of the Calculator buffer.

The `<' and `>' keys are bound to `calc-scroll-left' and
`calc-scroll-right'.  These are just like the normal horizontal
scrolling commands except that they scroll one half-screen at a time
by default.  (Calc formats its output to fit within the bounds of the
window whenever it can.)

The `{' and `}' keys are bound to `calc-scroll-down' and
`calc-scroll-up'.  They scroll up or down by one-half the height of
the Calc window.

The `M-# 0' command (`calc-reset'; that's `M-#' followed by a zero)
resets the Calculator to its default state.  This clears the stack,
resets all the modes, clears the caches (See Caches), and so on.
(It does *not* erase the values of any variables.)  With a numeric
prefix argument, `M-# 0' preserves the contents of the stack but
resets everything else.

The `M-x calc-version' command displays the current version number of
Calc and the name of the person who installed it on your system.
(This information is also present in the `*Calc Trail*' buffer, and in
the output of the `h h' command.)