feat: add arrow heads

fix: wasted space generated around the field

README.md

@@ -60,7 +60,7 @@ estimation size:
 dy/dx = 
 y/x
 range - format: (lower, upper): 
-(-10, 10)
+(-20, 20)
 estimation size: 
 0.1
 ```

app/Main.hs

@@ -7,6 +7,8 @@ module Main where
   import Graphics.Rendering.Chart.Backend.Cairo
   import Control.Lens
   import Data.Default.Class
+  import Data.Colour.SRGB
+  import Data.Colour
 
   main :: IO ()
   main = do
@@ -22,14 +24,18 @@ module Main where
 
     let chart = toRenderable layout
           where
+            color = opaque (sRGB 0.3 0.3 1)
+
             layout = layout_title .~ "slope field"
                    $ layout_plots .~ [vectors]
                    $ def
 
             vectors = plotVectorField
                     $ plot_vectors_values .~ field
-                    $ plot_vectors_scale .~ 0
-                    $ plot_vectors_style . vector_head_style . point_radius .~ 0
+                    $ plot_vectors_scale .~ 1
+                    $ plot_vectors_grid .~ []
+                    $ plot_vectors_style . vector_head_style . point_color .~ color
+                    $ plot_vectors_style . vector_line_style . line_color .~ color
                     $ def
 
     renderableToFile def "slope-field.png" chart

slope-field.cabal

@@ -1,5 +1,5 @@
 name:                slope-field
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            Visualize mathematical function's slope fields
 description:         Visualize mathematical function's slope fields
 homepage:            https://github.com/mdibaiee/slope-field
@@ -31,6 +31,7 @@ executable slope-field
                      , Chart-cairo
                      , lens
                      , data-default-class
+                     , colour
   default-language:    Haskell2010
 
 source-repository head

src/Lib.hs

@@ -18,4 +18,9 @@ module Lib
             half = diff / 2
             res = map (\(x, y) -> ((x - half, y), (half, d x y * diff))) pts
             inf = 1/0
-        in filter (\((x0, y0), (x, y)) -> x < inf && y < inf && x > -inf && y > -inf) res
+            noinf = filter (\((x0, y0), (x, y)) -> x < inf && y < inf && x > -inf && y > -inf) res
+            (minx, miny) = head pts
+            (maxx, maxy) = last pts
+            limitX = min maxx . max minx
+            limitY = min maxy . max miny
+        in map (\((x0, y0), (x1, y1)) -> ((limitX x0, limitY y0), (limitX x1, limitY y1))) noinf