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Show HN: Calc – A fast and intuitive command-line calculator written in Go

94 points by alfredxing 12y ago

clarry 12y ago
An alternative that isn't discussed in the Why not use ...? section is calc: http://www.isthe.com/chongo/tech/comp/calc http://www.isthe.com/chongo/tech/comp/calc It is very powerful, has history, shows previous calculations, and it's pretty darn quick too. Of course, there are plenty more calculators, powerful too. I only mention calc because it bothers me that the name of this new project collides with it, without really providing anything useful beyond having been written in a fashionable language.
- alfredxing 12y ago
  Did not know about this. It looks great, I'll definitely be trying it out! The project name was originally calc.go, but as you can imagine that didn't work out too well with `go get`.
- brute 12y ago
  Upvoted for calc. I use it for all the small calculation, as it most often behaves slightly better than bc $ echo "1/2" | bc 0 $ echo "1/2" | bc -l .50000000000000000000 $ echo "scale=1; 1/2" | bc .5 $ echo "1/2" | calc -p 0.5 $ echo "+1+1+1+1" | bc -l (standard_in) 1: syntax error $ echo "+1+1+1+1" | calc -p 4 $ echo "sqrt(-1)" | bc -l Runtime error (func=(main), adr=4): Square root of a negative number $ echo "sqrt(-1)" | calc -p 1i $ echo "s(pi)" | bc -l 0 $ echo "sin(pi())" | calc -p 0
  - tartrate 12y ago
    Slightly shorter, and it's nice to have the expression at the end of the line: $ bc -l <<< "1+1"
- mackal 12y ago
  I've been using wcalc personally, haven't had many reasons to use something else.
  - donpdonp 12y ago
    wcalc is pretty much the best terminal-mode calculator anywhere. It handles significant digits very well and knows about a bunch of mathematical constants in unicode form! -> √7×2÷π−ε0×σ+α+γ+R∞×Mτ-Φ0 = 2.26885 http://w-calc.sourceforge.net/download.php http://w-calc.sourceforge.net/download.php
    - voltagex_ 12y ago
      and it's apt-gettable from wheezy upwards!
- chanux 12y ago
  Thanks for bringing the original(?) calc to light. without really providing anything useful beyond having been written in a fashionable language The latter part of your comment sounds a bit discouraging. I think the developer didn't mean any harm an probably didn't know about this one. PS: The dev had replied in the thread. All is well I guess.
- chanux 12y ago
  calc package is called apcalc on dbian/ubuntu.
- hobarrera 12y ago
  This developer could have at least chosen a different name. Two programs, same funcionality, same name. Haven't we learnt anything?
  - alfredxing 12y ago
    As I mentioned below, I chose "calc.go", but that didn't work well with the `go get` command, so I had to get rid of the ".go"
qguv 12y ago
I stopped using infix calculators a while back in favor of RPN/stack calculators (dc) because I get quite tired of parens. Is the program structured such that this change would be simple? Otherwise I feel like this is simply yet another CLI calculator.
- alfredxing 12y ago
  The algorithm I use combines shunting-yard and postfix (RPN) evaluation, but I guess it wouldn't be too hard to modify the source to just do the RPN part. If you want to try that, the relevant code is the Evaluate function in `compute/compute.go`. A Google search for "command line calculator" doesn't turn up much, so I honestly didn't think there were many decent ones out there (aside from dc/bc). Are there any you have in mind?
- alfredxing 12y ago
  Obligatory XKCD: http://xkcd.com/645/ http://xkcd.com/645/
- shiggerino 12y ago
  I use the M-x calc in Emacs for this reason.
  - agumonkey 12y ago
    I find emacs calc very fitting the RPN tradition (reminiscent of HP pocket calculators), since it provides an algebraic solver; always a pleasurable thing to witness.
- bernalex 12y ago
  Incidentally I wrote a simple CLI RPN calc in half an hour recently: https://github.com/alexander-b/clac https://github.com/alexander-b/clac I was planning on adding a REPL-mode to it today for fun, and then someone linked me this post, saying "this could have been clac!", hehe.
- ConceptJunkie 12y ago
  People interested in this calculator might be interested in my project, which is written in Python: https://github.com/ConceptJunkie/rpn https://github.com/ConceptJunkie/rpn My rpn calculator started out comparable to the project described here, once I discovered the mpmath library, the project took on a life of its own and now has over 400 operations covering basic math, number theory, combinatorics, unit conversions (comparable to the GNU units program, or the Frink programming language), algebra and anything else that strikes my fancy.
Edmond 12y ago
Also checkout http://www.jasymchat.com http://www.jasymchat.com, it is a mobile version of Jasymca, A Java based computer algebra system.
brockrockman 12y ago
Emacs natives should know "C-x * *". Worth learning the bin/hex support with "d 2", "d 6".
EmanueleAina 12y ago
Qalculate has both a GUI and a command-line `qalc` util that does what `calc` seems to do and much more: http://qalculate.sourceforge.net/ http://qalculate.sourceforge.net/
soroushjp 12y ago
Other comments are reasonable, but fantastic work alfredxing, played around with it just now and loved how simple and intuitive it was. The only feature I really miss here is being able to use the previous answer -- is this there and I just didn't find it? Thinking of an 'ans' constant that holds the previous answer
- alfredxing 12y ago
  Thanks, and great suggestion! Would you mind opening an issue on GitHub for it? I'll probably get around to implementing it soon.
  - soroushjp 12y ago
    Sorry HN doesn't have reply notifications and just saw this, just added the issue!
element11 12y ago
Nice and great job ! I should switch to this. I have been using python until now. function calc { python -c "from math import *; print $1" }
- tartrate 12y ago
  You might like https://github.com/Russell91/pythonpy https://github.com/Russell91/pythonpy then.
commondream 12y ago
Nice! I wrote one called maths a while back. It's in Ruby but I use it pretty regularly and it does the trick: https://github.com/commondream/maths https://github.com/commondream/maths
redthrow 12y ago
Why not use.. Scientific Calculator (PowerCalc) for Android? https://play.google.com/store/apps/details?id=com.scaleasw.powercalc https://play.google.com/store/apps/details?id=com.scaleasw.p...
- mjcohen 12y ago
  My personal prejudice: I reject any calculator that does not compute the Gamma function (or factorial of non-integer arguments). Therefore, I reject this one.
otabdeveloper 12y ago
Use Tab instead: http://bitbucket.org/tkatchev/tab http://bitbucket.org/tkatchev/tab Includes a calculator, but also a complete declarative data-processing language too. E.g.: $ tab "[ log(@),@ : count(5) ]" 0 1 0.693147 2 1.09861 3 1.38629 4 1.60944 5
EugeneOZ 12y ago
Every small tool deserves special launching site and promoting if it's "written in go" or some other hyped language.
- redthrow 12y ago
  Most developers can't create something new and original or improve upon what's best out there so they reinvent things with very limited functions with something that people think is cool today (in this case, golang).
v-yadli 12y ago
I thought you mean calc.exe

94 points by alfredxing 12y ago

An alternative that isn't discussed in the Why not use ...? section is calc: http://www.isthe.com/chongo/tech/comp/calc http://www.isthe.com/chongo/tech/comp/calc It is very powerful, has history, shows previous calculations, and it's pretty darn quick too. Of course, there are plenty more calculators, powerful too. I only mention calc because it bothers me that the name of this new project collides with it, without really providing anything useful beyond having been written in a fashionable language.

alfredxing 12y ago
Did not know about this. It looks great, I'll definitely be trying it out! The project name was originally calc.go, but as you can imagine that didn't work out too well with `go get`.
brute 12y ago
Upvoted for calc. I use it for all the small calculation, as it most often behaves slightly better than bc $ echo "1/2" | bc 0 $ echo "1/2" | bc -l .50000000000000000000 $ echo "scale=1; 1/2" | bc .5 $ echo "1/2" | calc -p 0.5 $ echo "+1+1+1+1" | bc -l (standard_in) 1: syntax error $ echo "+1+1+1+1" | calc -p 4 $ echo "sqrt(-1)" | bc -l Runtime error (func=(main), adr=4): Square root of a negative number $ echo "sqrt(-1)" | calc -p 1i $ echo "s(pi)" | bc -l 0 $ echo "sin(pi())" | calc -p 0
- tartrate 12y ago
  Slightly shorter, and it's nice to have the expression at the end of the line: $ bc -l <<< "1+1"
mackal 12y ago
I've been using wcalc personally, haven't had many reasons to use something else.
- donpdonp 12y ago
  wcalc is pretty much the best terminal-mode calculator anywhere. It handles significant digits very well and knows about a bunch of mathematical constants in unicode form! -> √7×2÷π−ε0×σ+α+γ+R∞×Mτ-Φ0 = 2.26885 http://w-calc.sourceforge.net/download.php http://w-calc.sourceforge.net/download.php
  - voltagex_ 12y ago
    and it's apt-gettable from wheezy upwards!
chanux 12y ago
Thanks for bringing the original(?) calc to light. without really providing anything useful beyond having been written in a fashionable language The latter part of your comment sounds a bit discouraging. I think the developer didn't mean any harm an probably didn't know about this one. PS: The dev had replied in the thread. All is well I guess.
chanux 12y ago
calc package is called apcalc on dbian/ubuntu.
hobarrera 12y ago
This developer could have at least chosen a different name. Two programs, same funcionality, same name. Haven't we learnt anything?
- alfredxing 12y ago
  As I mentioned below, I chose "calc.go", but that didn't work well with the `go get` command, so I had to get rid of the ".go"

qguv 12y ago

I stopped using infix calculators a while back in favor of RPN/stack calculators (dc) because I get quite tired of parens. Is the program structured such that this change would be simple? Otherwise I feel like this is simply yet another CLI calculator.

alfredxing 12y ago
The algorithm I use combines shunting-yard and postfix (RPN) evaluation, but I guess it wouldn't be too hard to modify the source to just do the RPN part. If you want to try that, the relevant code is the Evaluate function in `compute/compute.go`. A Google search for "command line calculator" doesn't turn up much, so I honestly didn't think there were many decent ones out there (aside from dc/bc). Are there any you have in mind?
alfredxing 12y ago
Obligatory XKCD: http://xkcd.com/645/ http://xkcd.com/645/
shiggerino 12y ago
I use the M-x calc in Emacs for this reason.
- agumonkey 12y ago
  I find emacs calc very fitting the RPN tradition (reminiscent of HP pocket calculators), since it provides an algebraic solver; always a pleasurable thing to witness.
bernalex 12y ago
Incidentally I wrote a simple CLI RPN calc in half an hour recently: https://github.com/alexander-b/clac https://github.com/alexander-b/clac I was planning on adding a REPL-mode to it today for fun, and then someone linked me this post, saying "this could have been clac!", hehe.
ConceptJunkie 12y ago
People interested in this calculator might be interested in my project, which is written in Python: https://github.com/ConceptJunkie/rpn https://github.com/ConceptJunkie/rpn My rpn calculator started out comparable to the project described here, once I discovered the mpmath library, the project took on a life of its own and now has over 400 operations covering basic math, number theory, combinatorics, unit conversions (comparable to the GNU units program, or the Frink programming language), algebra and anything else that strikes my fancy.

Edmond 12y ago

Also checkout http://www.jasymchat.com http://www.jasymchat.com, it is a mobile version of Jasymca, A Java based computer algebra system.

brockrockman 12y ago

Emacs natives should know "C-x * *". Worth learning the bin/hex support with "d 2", "d 6".

EmanueleAina 12y ago

Qalculate has both a GUI and a command-line `qalc` util that does what `calc` seems to do and much more: http://qalculate.sourceforge.net/ http://qalculate.sourceforge.net/

soroushjp 12y ago

Other comments are reasonable, but fantastic work alfredxing, played around with it just now and loved how simple and intuitive it was. The only feature I really miss here is being able to use the previous answer -- is this there and I just didn't find it? Thinking of an 'ans' constant that holds the previous answer

alfredxing 12y ago
Thanks, and great suggestion! Would you mind opening an issue on GitHub for it? I'll probably get around to implementing it soon.
- soroushjp 12y ago
  Sorry HN doesn't have reply notifications and just saw this, just added the issue!

element11 12y ago

Nice and great job ! I should switch to this. I have been using python until now. function calc { python -c "from math import *; print $1" }

tartrate 12y ago
You might like https://github.com/Russell91/pythonpy https://github.com/Russell91/pythonpy then.

commondream 12y ago

Nice! I wrote one called maths a while back. It's in Ruby but I use it pretty regularly and it does the trick: https://github.com/commondream/maths https://github.com/commondream/maths

redthrow 12y ago

Why not use.. Scientific Calculator (PowerCalc) for Android? https://play.google.com/store/apps/details?id=com.scaleasw.powercalc https://play.google.com/store/apps/details?id=com.scaleasw.p...

mjcohen 12y ago
My personal prejudice: I reject any calculator that does not compute the Gamma function (or factorial of non-integer arguments). Therefore, I reject this one.

otabdeveloper 12y ago

Use Tab instead: http://bitbucket.org/tkatchev/tab http://bitbucket.org/tkatchev/tab Includes a calculator, but also a complete declarative data-processing language too. E.g.: $ tab "[ log(@),@ : count(5) ]" 0 1 0.693147 2 1.09861 3 1.38629 4 1.60944 5

EugeneOZ 12y ago

Every small tool deserves special launching site and promoting if it's "written in go" or some other hyped language.

redthrow 12y ago
Most developers can't create something new and original or improve upon what's best out there so they reinvent things with very limited functions with something that people think is cool today (in this case, golang).

v-yadli 12y ago

I thought you mean calc.exe