wrapdc - Command line wrapper for
wrapdc [-v] [pseudocommand] [command]
This wrapper renders
dc more usable as a command line calculator by:
/tmp/wdc-$USERfor further direct use (change file name in the source, if desired)
The POSIX conform program
dc ("desktop calculator") and standard shell
must be installed and accessible through
The wrapper script
wrapdc.sh can be called directly (if executable) or by
sh wrapdc.sh with optional arguments.
If arguments are given, they are interpreted as one line of commands, which is executed, and then the script finishes.
If no arguments are given, the script enters a loop: read a line
of input from STDIN, execute it, and display the resulting top-of-stack,
together with the top of stack in exponential notation
(which currently only works as usual for absolute values greater than 1).
The loop (and script) finishes, when
quit or CTRL-D is entered.
dc commands can be used, see the corresponding manual.
In particular, negative numbers must be entered with a leading
(underscore) as minus sign, not a
- (dash), because the latter is
indicating the command 'subtraction'.
As an extension, values can also be entered in exponential notation,
12e3 is converted to
.01 (if precision is 2).
r (exchanging the two topmost stack entries) is emulated
with some internal register operations, as it is a GNU extension and may not
always be available. This may render complex operations somewhat slower.
There is also a macro
drop for removing the topmost stack value.
In addition to the
quit command, the following pseudocommands are handled
directly by the wrapper:
helpshows some initial hints and this pseudocommand list
listdisplays a list of predefined macros; please note the syntax is according to
sedi.e certain characters are escaped with backslash
verbactivates verbose mode, which displays before each execution of input line the input from the status file as well as the input line with expanded macro definitions
noverbdeactivates verbose mode
clearresets precision and all memories and stack registers
All pseudocommands must be entered at the beginning of a line, and all subsequent input on this line will be ignored.
Verbose mode can also be activated with the command line option
may be useful in case of direct input with further command line arguments.
The registers ("memories") 1 to 6 have special meanings for statistical
$... macros, and are used as follows:
$+ adds the two topmost stack values to the statistical
registers as follows: the topmost value is added to reg.2 and its square
value to reg.3, the second to topmost value in the same way to reg.4 and 5,
and the product of the two values to reg.6. reg.1 is then increased by 1.
$- subtracts the values in the inverse way. Please note: due to
$- is not the inverse of
$+ in some cases.
$m calculates the mean values reg.2/reg.1 and reg.4/reg.1.
(More commands will be added in future versions.)
wrapdc.sh is executable in
$ wrapdc.sh 5k 2v # precision 5, 2 on stack, calculate square root 1.41421 # 1.41421E0 $ wrapdc.sh 3 7/ # 3, divide by 7 (precision was saved from last run) .42857 # 4.28570E-1 $ wrapdc.sh list # display macros (and top of stack before finishing) : %t # percent part: X:=100*X/Y, Y kept : %d # percent delta: X:=100*(X-Y)/Y, Y kept : % # percentage: X:=X*Y/100, Y kept : rem # remainder: X:=Y%X (instead of normal % command) : sto\(.\) # sto.: store with copying (i.e keep value on stack) : fact # factorial: X:=X! : neg # negate: X:=-X : \$m # mean value: X:=reg.2/reg.1, Y:=reg.4/reg.1 : \$- # remove statistic entry : \$+* # add statistic entry : [eE]\(_*[0-9][0-9]*\) # infix exponential: X:=X*10^N : drop # stack drop : r # revert: X:=Y, Y:=X (r is a GNU extension) .42857 # 4.28570E-1 $ wrapdc.sh 42fact sto1 # calculate 42! (factorial) and store in '1' 1405006117752879898543142606244511569936384000000000 # 1.40500E51 $ wrapdc.sh 2k234 7%+ # precision 2, add 7% to 234 250.38 # 2.50E2 $ wrapdc.sh 234r%t # which is how many % of 234? 107.00 # 1.07E2 $ wrapdc.sh l1 40fact/ # divide memory '1' by the factorial of 40 1722.00 # 1.72E3 $ wrapdc.sh 41 42* # which of course is 42!/40!=41*42 1722 # 1.72E3 $ wrapdc.sh clear # set all registers to 0 (prepare for statistics) 0 # 0E-1 $ wrapdc.sh '1$2$3$4$l2' # entries: 1,2,3,4; load reg.2 (sum) 10 # 1.00E1 $ wrapdc.sh '$m' # display average of statistic entries 2.50 # 2.50E0 $ wrapdc.sh 1234fact|sed -e 's/.*#//' # 1234!, only display exponential 5.10E3280 $ wrapdc.sh 1233fact/ # just checking: 1234!/1233!=1234 1234.00 # 1.23E3 $ wrapdc.sh 1.23e3- # just checking exponential notation 4.00 # 4.00E0
Note: the example with
41 42* only works if there is no file
beginning with '42' in the current directory, otherwise the shell
will expand its name before passing on the argument to the wrapper
script. In this case, you should escape the
* or put the arguments
'41 42*' or simply start the wrapper without
arguments, and do the calculations in its internal command loop.
Preventing shell expansion is also necessary in the statistics example.
Macros can be easily added to the script, if you know
They are defined in the shell variable
mcrs. where each one should be
written on a separate line with comma
, as pattern delimiters, followed
;# and a comment explaining its use.
This allows the
list pseudocommand to display them together with the
comment. Do not prepend any white space to the definition, otherwise
it will not be displayed by
Please note that the macro expansion is global and "stupid" — you should
therefore define the longer commands first, and single character commands
only at the very end. Otherwise, e.g the
rem command would first have its
r expanded as the "revert" command, therefore
rem expansion would fail.
$HOME/.wdcrcas a list of
These file names can be easily changed at the beginning of the script.
(certainly, but none known at this moment)