[SOLVED] commandline calculator

kokoko3k · 2015-06-26 06:45:44

With this in ~/.bashrc

= () { echo "$*" | bc -l ; }

I can simply type:

# = 3/4
.75000000000000000000

...which is handy, but if i want to use parentheses, i must enclose the whole expression by double quotes (or quote parentheses)
Is there a smart way to avoid it?

# = "((3/4)+1)/2"
.87500000000000000000
= ((3/4)+1)/2 
bash: syntax error near unexpected token `('

thanks

Last edited by kokoko3k (2015-06-29 14:40:10)

ewaller · 2015-06-26 15:48:32

backslash quote the parentheses

ewaller@turing ~ 1076 %= \(1 + 2\)/3
1.00000000000000000000
ewaller@turing ~ 1077 %

Or, use dc instead of bc and enter the equation using RPN

Last edited by ewaller (2015-06-26 15:50:36)

teckk · 2015-06-26 17:38:26

Also have a look at extra/genius

genius> 3/4
= 3/4
genius> 3/4.0
= 0.75
genius> 3/4 + 1/2
= 1 1/4
genius> 3/4 + 1/2.0
= 1.25
genius> ((3/4)+1)/2
= 7/8
genius> ((3/4)+1.0)/2
= 0.875

kokoko3k · 2015-06-26 18:38:03

Thanks, genius is nice, but i'd like to use something lighter and not interactive.
Ewaller, i prefer the double quotes to RPN

falconindy · 2015-06-27 15:42:46

You can't avoid the escaping because you're asking the shell to interpret your text before it's passed to the function. If you instead:

=() { bc -ql; }

Then you can...

$ =
((3/4)+1)/2
.87500000000000000000
3/4
.75000000000000000000

Requires a few extra keystrokes (including ^D to leave bc), but you can avoid the need for escaping. Perhaps you can go one step further...

=() {
  if (( $# )); then
    echo "$*" | bc -l
  else
    bc -ql
  fi
}

Now you get interactivity if you call '=' without args and accept the pitfalls, or you just type '=' and get an interactive calculator.

kokoko3k · 2015-06-29 14:39:57

Yes yes, understood.
Marking as solved, thank you all.

esa · 2015-06-29 14:45:56

I like awk to do math:

echo 15 4 5 | awk '{print ($1 / $2 * $3)}'

Procyon · 2015-06-30 12:47:53

Check this out, using bash's bind -x (so source it or put it in .bashrc):

bind -x '"=": if [[ "$READLINE_LINE" == =* ]]; then
	echo -e "$(bc <<< "${READLINE_LINE:1}" 2>&1) \e[33m(${READLINE_LINE:1})\e[m"
else
	READLINE_LINE=${READLINE_LINE:: $READLINE_POINT}=${READLINE_LINE: $READLINE_POINT}
	((READLINE_POINT++))
fi'

Type = and then an equation and then =. The equation stays on the prompt so you can edit it further and you can type = anywhere on the line.

72 (9*8)
288 (9*8*2*2)
144 (9*8*2*1)
(standard_in) 1: syntax error (9*8*2*1 4)
█ /1/bin █ =9*8*2*1 4

Last edited by Procyon (2015-07-13 17:30:41)

kokoko3k · 2015-07-03 17:24:23

Very nice Procyon, now it is just a matter of taste

Trilby · 2015-07-03 19:06:04

You may also like these two posts. That is if you want to try interrobang as a calculator (but note the syntax of the config file has changed since then).

Arch Linux

#1 2015-06-26 06:45:44

[SOLVED] commandline calculator

#2 2015-06-26 15:48:32

Re: [SOLVED] commandline calculator

#3 2015-06-26 17:38:26

Re: [SOLVED] commandline calculator

#4 2015-06-26 18:38:03

Re: [SOLVED] commandline calculator

#5 2015-06-27 15:42:46

Re: [SOLVED] commandline calculator

#6 2015-06-29 14:39:57

Re: [SOLVED] commandline calculator

#7 2015-06-29 14:45:56

Re: [SOLVED] commandline calculator

#8 2015-06-30 12:47:53

Re: [SOLVED] commandline calculator

#9 2015-07-03 17:24:23

Re: [SOLVED] commandline calculator

#10 2015-07-03 19:06:04

Re: [SOLVED] commandline calculator

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