Grouping Digits
---------------

Long numbers can be hard to read if they have too many digits.  For
example, the factorial of 30 is 33 digits long!  Press `d g'
(`calc-group-digits') to enable "grouping" mode, in which digits are
displayed in clumps of 3 or 4 (depending on the current radix)
separated by commas.

The `d g' command toggles grouping on and off.  With a numerix prefix
of 0, this command displays the current state of the grouping flag;
with an argument of minus one it disables grouping; with a positive
argument `N' it enables grouping on every `N' digits.  For
floating-point numbers, grouping normally occurs only before the
decimal point.  A negative prefix argument `-N' enables grouping every
`N' digits both before and after the decimal point.

The `d ,' (`calc-group-char') command allows you to choose any
character as the grouping separator.  The default is the comma
character.  If you find it difficult to read vectors of large integers
grouped with commas, you may wish to use spaces or some other
character instead.  This command takes the next character you type,
whatever it is, and uses it as the digit separator.  As a special
case, `d , \' selects `\,' (TeX's thin-space symbol) as the digit
separator.

Please note that grouped numbers will not generally be parsed
correctly if re-read in textual form, say by the use of `M-# y' and
`M-# g'.  (See Kill and Yank, for details on these commands.)  One
exception is the `\,' separator, which doesn't interfere with parsing
because it is ignored by TeX language mode.