Operating the linear algebra library in Haskell and using the matrix and gnuplot Plot Method

Haskell's native data structure is not efficient for large-scale mathematical operations. Using list to store vectors or matrices is inefficient. Fortunately, Haskell has a wealth of third-party libraries that can be used to complete this operation with a powerful professional mathematical library. We will introduce the hmatrix library today.

 

1. Installation

Development Environment: MacOSX 10.5

1. Install the dependent Library

GSL (
GNU Scientific Library
), Go to the GNU website to download the source code and compile it by yourself.

2. Install hmatrix, gnuplot, and so on. Use cabal install.

 

 

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II. Introduction

1. Matrix generation and operations

 

Data. Packed. Matrix

 

(> <)
: Element
A => int
-> Int
-> [A]-> Matrix
A

 

> <This operator is used to define the rows and columns of a matrix. Its shape is like the X operator.

 

Test:

 

M1 = (3> <4) [1 ..]: matrix double

 

The corresponding matrix is:

 

1 2 3 4

5 6 7 8

9 10 11 12

 

2. Modify the value of the matrix element in-place

Use status monad

 

Import data. Packed. St
Import Control. monad. St

 

Testupdatemat: matrix double
Testupdatemat = runstmatrix $ do
M <-newmatrix 0 3 4
Writematrix M 0 0 1
Writematrix M 2 3 4
Return m

The matrix returned by testupdatemat, newmatrix first creates a 3x4 matrix with 0 values, and writematrix M 0 0 1 modifies the value of M (0, 0) to 1, writematrix M 2 3 4 change the (2, 3) position value to 4

 

The final result is:

 

1 0 0 0

0 0 0 0

0 0 0 4

 

3. Plot Using Plot

Directly add the code and, But I have explained more.

 

Import graphics. Plot

Vector xs = fromlist Xs: Vector Double

Plot2d F n = mesh (f x Y) Where
(X, y) = meshdom Range
Range = linspace N (-2, 2)

Sombrero x y = exp (-R2) * Cos (2 * R2)
Where r2 = x * x + y * y

F x = SiN x + 0.5 * sin (5 * X)

 

Main = do
Let X = linspace 1000 (-4, 4)
Mplot [f x]
Plot2d sombrero 40