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Quick and dirty plotting with Haskell: Supplement

Posted 01-14-2013 at 11:54 PM by hydraMax (Bits and Pixels)

I just wanted to add a brief note to my previous post: It is also quite simple to do a plot with multiple functions. The following code gives the graph seen in the attached PNG:

Code:

h> import Graphics.Gnuplot.Simple
h> let f x = 3 - 2*x + 4*x**2
h> let g x = 8*x - 2
h> let h a x = g a * (x - a) + f a
h> plotFuncs [] (linearScale 1000 (-10,10)) [f, g, h (-5)]

f(x) is a function, g(x) is the derivative of f(x), and...

Attached Images

plotFuncs.png (49.5 KB, 4 views)

hydraMax

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Installed Nix

Posted 01-09-2013 at 01:49 PM by hydraMax (Bits and Pixels)

Tags nix

I recently installed the Nix package manager on my system:

https://nixos.org/nix/

Nix is an intriguing idea: a purely functional and deterministic package management system. Nix allows you to install, upgrade, and remove packages on your system without ever having to worry about breaking the dependencies of other packages already installed on your system. This is impossible, by design. Likewise, after installing new packages, you are free to roll back those changes...

hydraMax

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haskell: get lines and handle end of file

Posted 01-01-2013 at 02:23 AM by hydraMax (Bits and Pixels)
Updated 01-01-2013 at 02:27 AM by hydraMax

Tags haskell

I thought I'd post this convenience function, since I didn't see an obvious one in base:

Code:

import Prelude hiding (catch)
import Control.Exception
import System.IO.Error hiding (catch)

readl f = catch (getLine >>= return . Just)
                (\e -> if (isEOFErrorType . ioeGetErrorType) e
                         then return Nothing
                         else ioError e)
          >>= \a -> case a of

...

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Quick and dirty plotting with Haskell + Gnuplot

Posted 12-28-2012 at 05:13 PM by hydraMax (Bits and Pixels)
Updated 12-28-2012 at 05:17 PM by hydraMax

Tags haskell

Assuming you are a Haskeller, you can get a simply x-y plot up very quickly with the gnuplot interface module. This is useful for getting a rough graphical view of some function. Simply...

1. install Gnuplot (through your package manager)
2. cabal install gnuplot
3. use ghci:

Code:

$ ghci
GHCi, version 7.4.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ...

...

Attached Images

image3023.png (29.8 KB, 3 views)

hydraMax

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