When you do math in bc it clearly uses some order of operations. And I know that this falls within the realm of Reverse Polish Notation; so is it possible for it to explain itself? I mean I know I can do order of operations on my own, but recently there's been some disagreement online about this, and it would be good to be able to determine if someone used PEMDAS or something else to calculate their result. If each of the steps were shown within the program that would clear all of that up.

I am using the bc calculator with obase and ibase to convert integer representation. I'm not used to it, because very basic things can be done with $(( expresion )) in bash, and most things that can't be done with that are prone to get more complicated in the future, and then, perl or java are the tools of choice. What I have done is helper@gg$ echo 'obase=10; ibase=16;F;' | bc 15 helper@gg$ echo 'ibase=16; obase=10;F;' | bc F helper@gg$ echo 'ibase=16; obase=10;10;' | bc 10 helper@gg$ echo 'obase=10; ibase=16;10;' | bc 16 helper@gg$ and the result obviously depends on the order in which ibase and obase are given. Naturally, I've taken a look at the bc manpage but found noting about this. Question is: how does it work, and where can I read more about this, to avoid other pitfalls in the like of this.

#!/bin/bash q=$(bc secondcoordinate.txt That's just part of the script, but I think it's enough to clarify my intentions. p is a variable with just two decimals, so q should be an integer... Nevertheless, bc shows, for example, 10.00 instead of 10. How can I solve this?

What are the differences between dc and bc calculators? When should I use dc and when bc?

How do I get bc to start decimal fractions with a leading zero? $ bc <<< 'scale=4; 1/3' .3333 I want 0.3333.

In Ubuntu 14.04.1 LTS 64-bit bash I am declearing floating point variables by multiplying floating point bash variables in bc with scale set to 3; however, I cannot get the number of digits after the decimal point to be zero and get rid of the zero to the left of the decimal point. How can I transform, say 0.005000000 into .005? This is necessary due to my file naming convention. Thanks for your recommendations. UPDATE: Can I use it for already defined shell variables and redefining them? The following code gives me an error. ~/Desktop/MEEP$ printf "%.3f\n" $w bash: printf: 0.005000: invalid number 0,000 The output of locale @vesnog:~$ locale LANG=en_US.UTF-8 LANGUAGE=en_US LC_CTYPE="en_US.UTF-8" LC_NUMERIC=tr_TR.UTF-8 LC_TIME=tr_TR.UTF-8 LC_COLLATE="en_US.UTF-8" LC_MONETARY=tr_TR.UTF-8 LC_MESSAGES="en_US.UTF-8" LC_PAPER=tr_TR.UTF-8 LC_NAME=tr_TR.UTF-8 LC_ADDRESS=tr_TR.UTF-8 LC_TELEPHONE=tr_TR.UTF-8 LC_MEASUREMENT=tr_TR.UTF-8 LC_IDENTIFICATION=tr_TR.UTF-8 LC_ALL= The output of echo $w @vesnog:~$ echo $w 0.005000

[POSIX.1-2001](https://pubs.opengroup.org/onlinepubs/009695399/) [Utilities](https://pubs.opengroup.org/onlinepubs/009695399/idx/utilities.html) and [POSIX.1-2008](https://pubs.opengroup.org/onlinepubs/9699919799/) [Utilities](https://pubs.opengroup.org/onlinepubs/9699919799/idx/utilities.html) both list the commands bc and ed to be part of POSIX. Yet, in a brand new Debian installation (version 10 for example), these commands are missing by default:

$ bc
bash: bc: command not found
$ ed
bash: ed: command not found

Why does Debian not include these commands by default? Of course, I can install them with and I did that.

apt-get install bc ed

The bc binary is only 87K in size. The entire package including the man page and documentation is only 209K in size. Similarly the ed binary is only 55K in size. The entire package is only 93K in size. What good reason is there not to include these tiny packages even though they are specified in POSIX?

This is a **self-answered** question, the research that is reasonable to ask for a question goes in the answer part, Please do not downvote because you believe I have not researched enough for an answer. Thanks. In any case, there is no description (that I can find) of this characteristic of bc in this site. When using bc, the % operator is claimed to calculate the "remainder", and yes, it works for integer numbers and when the **scale is zero**: $ bc <<<' scale=0; 27 % 7 ' 6 But it fails to give the "integer remainder" if the scale is not zero: $ bc <<<' scale=10; 27 % 7 ' .0000000003 Why (or how) is this definition of the % modulo useful?

The Linux kernel minimal building requirements specifies that the calculator bc is required to build kernel v4.10, the minimal version of the tool being 1.06.95. What use is made of bc in this context, and why isn't the C language directly used instead of bc for these operations?

Consider the following:

$ echo "-1" | bc
-1

$ echo "(1)" | bc
1

$ echo "+1" | bc
(standard_in) 1: syntax error

Minus sign and round braces are handled correctly but when explicit plus sign is specified bc falls with error. Is it possible to make it treat explicitly positive numbers just as normal positive numbers? I want to be able to calculate constructions like: - +1++2 (result must be 3) Even simple Ubuntu calculator can do such operations: It is strange that bc can't. Seems like a bug. As a workaround sed can be used to preprocess the input for bc, or perhaps bc has some specific config for this? Or may be there is some alternative to bc for that? --- **Update** I've sent request to bc's support team to consider to fix this bug. Comments from [Kusalananda](https://unix.stackexchange.com/users/116858/kusalananda) : > bc is a POSIX utility, and any implementation of the utility > therefore should follow the [POSIX specification](https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/utilities/bc.html) . This specification > contains a grammar which does not include the unary plus operation. If > GNU implements a unary plus in their implementation of bc, they > would need to ensure that all existing code that uses bc still > performs as before and that any future code that uses bc performs as > a reader of the standard would expect. > > Also note that -1--2 is an error, so you seem to additionally > propose a change in the precedence of the increment and decrement > operators, right? My comment: > I think that bc should be able to perform simple calculations like > simple calculator can do. If support team adds to bc at least > ability to handle cases with digits like -1--2 (with result 1) and > +1++2 (with result 3) (only unary plus operation for digits, and not falling with error while trying to execute increment / decrement > operations on digits which all the same are not supported by now) in my understanding it will > not anyhow impact existing or future POSIX-compliant code.

I just wrote a small bash shell script and for the first time in that context I wanted to make a calculation, a division, and discovered bc. My script processes media files and I want to log the performance, that is, the length of the file divided by the duration of the processing. Typical values for the quotient is 0,03-0,05 but bc doesn't round, it truncates! Which is a problem because the difference between 0,0300 and 0,0399 is quite significant but bc will return 0,03 for both. I have read multiple questions about making bc round, with mostly quite convoluted solutions. This made me wonder: **Why doesn't bc have native support for rounding??** I am not looking for a solution but am curious about the design decisions behind the lack of support for rounding. I am aware of the KISS philosophy but rounding floating point values is such a basic feature for any calculator. Of course you could display the result with two more digits and the make the rounding manually (in your head), but it is weird to waste human mental energy a task that a computer is much better on performing than a human! Hence my question.

I have two old machines, running CentOS 6.5 and CentOS 6.10. Both have bc 1.06.95-1.el6 installed. One reads $HOME/.bc.rc, one does not. Why ? (How??) strace shows near-identical output, except one reads the config file. The libraries are identical.

I would like to use m4 interactively as a preprocessor for bc. My immediate use case is to add an include capability to bc, but I can foresee other uses in the future. But there is a problem. Here is an example using bc on its own:

`
$ bc
bc 1.07.1
Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
3+7
10
sqrt(12345)
111
quit
$

` And here is the same example using m4 interactively:

`
$ m4 -iP - | bc
3+7
10
sqrt(12345)
111
quit

$

` There are two differences. First, the m4 version suppresses the banner. Second, the m4 version doesn't execute quit immediately, but instead requires the enter key to be pressed an additional time before it executes the quit. Why do these things occur? How can I make the m4 version work the same way as the bc version?

I am trying to multiply array values with values derived from the multiplication of a loop index using bc. #!/bin/bash n=10.0 bw=(1e-3 2.5e-4 1.11e-4 6.25e-5 4.0e-5 2.78e-5 2.04e-5 1.56e-5 1.29e-5 1.23e-5 1.0e-5) for k in {1..11};do a=$(echo "$n * $k" | bc) echo "A is $a" arn=${bw[k-1]} echo "Arn is $arn" b=$(echo "$arn * $a" | bc -l) echo "b is $b" #echo $a $b done I am able to echo the array values by assigning it to a new variable within the loop, but when I use that to multiply using bc, I get (standard_in) 1: syntax error. I searched for clues and tried some but none helped. The expected output is as follows. 10 1.00E-02 20 5.00E-03 30 3.33E-03 40 2.50E-03 50 2.00E-03 60 1.67E-03 70 1.43E-03 80 1.25E-03 90 1.16E-03 100 1.23E-03 110 1.10E-03 All help is greatly appreciated.

**System**: - Ubuntu 22.04.3 LTS - GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) - bc 1.07.1 **Observation**: Both ibase and obase are unset. echo "A0" | bc 90 echo "B0" | bc 90 echo "X0" | bc 90 **Question**: Why does bc interpret alpha characters as 9s by default? Why wouldn't an error message be preferable here?

is it possible to integrate bc command line calculator in an app (script interpreter) as a library? I am not asking if that can be done, I am asking if there is something ready already that wraps bc and make it work as a library. In ubuntu 22.04 I can't find any packages like bc-dev libbc-dev libbc ... Searching for this subject on google doesnt help either. My goal is to integrate the command line calculator interpreter bc inside a GPL game script interpreter called Arx Libertatis (Arx Fatalis). So, when the game starts and it reads and interprets it's .asl script, it will find a line like ex.: Calc @result "(~@val1~*33)/~@val2~" (where ~@val1~ will expand to 0.25 and ~@val2~ will expand to 7.123) That script line shall send "(0.25*33)/7.123" to bc and assign it's result at @result. But for that, I need to access the bc main function directly and not call the compiled bc binary. So I am loogin for a libbc-dev somewhere, but I just can't find it. Will I have to wrap it in a lib myself? btw, it must have high performance, and if there is an alternative to bc that provides a faster result, it is important because it is a game and the calculations must happen as fast as possible. Also, I could use flags to the Calc script command to determine what calculator interpreter will be used so Calc -b ... would use bc, while Calc -d ... could use some other library (and therefore mod developers must prepare it in a syntax that is recognized by the other library).

I have a simple bash function dividing two numbers: echo "750/12.5" | bc I'd like to take the output from bc and append /24 and pipe said result to another instance of bc. Something like: echo "750/12.5" | bc | echo $1 + "/24" | bc Where $1 is the piped result. *P.S. I realize I could just do echo "750/12.5/24" | bc my question is more in regards to the appending of text to a pipe result.*

It looks like bc doesn't support float operations. When I do echo 1/8 | bc it gets me a zero. I checked the manual page bc (1), but it doesn't even mention float, so I wonder if it's supported?

I'm trying to find derive SCALEFACTOR which is basically 10000/(sum of 4th column in a file). How do I get a decimal from the output? Appreciate any help in advance. #!/bin/bash FILES=/path/to/files/*; for f in ${FILES} do echo $f COLTOTAL="$(awk '{sum += $4} END {print sum}' $f)" echo "total: ${COLTOTAL}" # SCALEFACTOR=expr 10^5 / $COLTOTAL B=10000 SCALEFACTOR=$((B / ${COLTOTAL})) SCALINGFACTOR=$(echo "100000 / $COLTOTAL" | bc -l # echo "scale=5; ${SCALEFACTOR}" | bc echo ${SCALEFACTOR} awk '{print($1"\t"$2"\t"$3"\t"$4 * ${SCALINGFACTOR})}' $f > $f"_normalized.txt" done

I am trying to write a code that will calculate the radius and area of a circle using pi and the circumference. When I try to run my code, I receive an error message that says

main.sh: line 5: bc: command not found
main.sh: line 7: bc: command not found

Could you please advise me on where I went wrong, and help me to fix my code? The code: #!/bin/bash pi=3.14; circumference=5; echo "$circumference" radius=$(echo "$circumference" \* 2 \* "$pi" |bc -l); echo "$radius" area=$(echo "$pi" \* "$radius" \* "$radius" |bc -l); echo "$area" echo "The radius of a circle is $radius"; echo "The area of a circle is $area"; exit