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5 years ago  

README.md  5 years ago  
wrapdc.sh  5 years ago 
README.md
NAME
wrapdc  Command line wrapper for dc (1)
SYNTAX
wrapdc [v] [pseudocommand] [command]
DESCRIPTION
This wrapper renders dc
more usable as a command line calculator by:
 defining commonly used macros for more complex operations
 saving precision, top of stack, and registers 0 to 9 ("memories")
from one invocation to the next in the status file
$HOME/.wdcrc
 saving last top of stack value in
${TMPDIR:/tmp}/wdc$USER
for further direct use (change file name in the source, if desired)
PREREQUISITES
The POSIX conform program dc
("desktop calculator") and standard shell sh
must be installed and accessible through $PATH
.
USAGE
The wrapper script wrapdc.sh
can be called directly (if executable) or by
invoking 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 topofstack,
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 CTRLD is entered.
All normal 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,
e.g 12e3
is converted to 1200
and 1E_2
to .01
(if precision is 2).
The dc
command 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:
help
shows some initial hints and this pseudocommand listlist
displays a list of predefined macros; please note the syntax is according tosed
i.e certain characters are escaped with backslashverb
activates 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 definitionsnoverb
deactivates verbose modeclear
resets 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 v
which
may be useful in case of direct input with further command line arguments.
Statistical Calculations
The registers ("memories") 1 to 6 have special meanings for statistical
calculations with $...
macros, and are used as follows:
 reg.1 = number of entries
n
 reg.2 = sum of X values
sumX
 reg.3 = sum of X^2 values
sumX2
 reg.4 = sum of Y values
sumY
 reg.5 = sum of Y^2 values
sumY2
 reg.6 = sum of XY values
sumXY
The command $
or $+
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.
The command $
subtracts the values in the inverse way. Please note: due to
rounding errors, $
is not the inverse of $+
in some cases.
The command $m
calculates the mean values reg.2/reg.1 and reg.4/reg.1.
(More commands will be added in future versions.)
EXAMPLES
(We assume wrapdc.sh
is executable in $PATH
.)
$ 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 # 4.28570E1
$ 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*(XY)/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]\(_*[09][09]*\) # infix exponential: X:=X*10^N
: drop # stack drop
: r # revert: X:=Y, Y:=X (r is a GNU extension)
.42857 # 4.28570E1
$ 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 # 0E1
$ 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 1234factsed 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
in apostrophes '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
Macros can be easily added to the script, if you know sed
syntax.
They are defined in the shell variable mcrs.
where each one should be
written on a separate line with comma ,
as pattern delimiters, followed
by ;#
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 list
!
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.
FILES
 The status between invocations is stored in the file
$HOME/.wdcrc
as a list ofdc
commands.  The last top of stack value is stored in
/tmp/wdc$USER
.
These file names can be easily changed at the beginning of the script.
BUGS
(certainly, but none known at this moment)
AUTHOR
Yargo Bonetti