wk5: Higher order functions, Modelling (pt.2)

This commit is contained in:
Dimitar Byalkov
2024-03-22 22:24:09 +01:00
parent 8eb9c65aa6
commit 303d110b90
4 changed files with 296 additions and 0 deletions

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wk5/elm.json Normal file
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{
"type": "application",
"source-directories": [
"src"
],
"elm-version": "0.19.1",
"dependencies": {
"direct": {
"elm/browser": "1.0.2",
"elm/core": "1.0.5",
"elm/html": "1.0.0"
},
"indirect": {
"elm/json": "1.1.3",
"elm/time": "1.0.0",
"elm/url": "1.0.0",
"elm/virtual-dom": "1.0.3"
}
},
"test-dependencies": {
"direct": {},
"indirect": {}
}
}

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wk5/src/HighOrder.elm Normal file
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module HighOrder exposing (..)
{-
Higher order functions
Dimitar Byalkov and Kaloyan Stoykov
-}
repeatUntil: (a -> Bool) -> (a -> a) -> a -> a
repeatUntil p f init =
let
fResult = f init
in
if not(p fResult) then
repeatUntil p f fResult
else
fResult
double: Int -> Int
double a =
a * 2
above100: Int -> Bool
above100 x =
x > 100
aboveN: Int -> (Int -> Bool)
aboveN n =
((<=) n)
log: Int -> Int -> Int
log base result =
if result == base then
1
else
log base ((repeatUntil (aboveN result) (\x -> base * x) base)
// base) + 1
myCollatz: List Int -> List Int
myCollatz values =
case values of
[] ->
[]
x :: _ ->
if modBy 2 x == 0 then
x // 2 :: values
else
(3 * x + 1) :: values
myPredicate: List Int -> Bool
myPredicate vals =
case vals of
[] ->
False
x :: _ ->
x == 1
-- Tests
testCollatzEven: Bool
testCollatzEven = repeatUntil myPredicate myCollatz [24] ==
[1,2,4,8,16,5,10,3,6,12,24]
testCollatzOdd: Bool
testCollatzOdd = repeatUntil myPredicate myCollatz [19] ==
[1,2,4,8,16,5,10,20,40,13,26,52,17,34,11,22,44,88,29,58,19]

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wk5/src/Modelling1.elm Normal file
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module Modelling1 exposing (..)
{-
Modelling Math Functions (part 1)
Dimitar Byalkov and Kaloyan Stoykov
-}
type Function
= Poly Function Int
| Mult Function Function
| Div Function Function
| Plus Function Function
| Minus Function Function
| Const Int
| X
print: Function -> String
print f =
case f of
X ->
"x"
Const val ->
String.fromInt val
Poly func val ->
"(" ++ print func ++ " ^ " ++ String.fromInt val ++ ")"
Mult func1 func2 ->
"(" ++ print func1 ++ " * " ++ print func2 ++ ")"
Div func1 func2 ->
"(" ++ print func1 ++ " / " ++ print func2 ++ ")"
Plus func1 func2 ->
"(" ++ print func1 ++ " + " ++ print func2 ++ ")"
Minus func1 func2 ->
"(" ++ print func1 ++ " - " ++ print func2 ++ ")"
eval: Float -> Function -> Float
eval num f =
case f of
X ->
num
Const val ->
toFloat val
Poly func val ->
eval num func ^ (toFloat val)
Mult func1 func2 ->
eval num func1 * eval num func2
Div func1 func2 ->
eval num func1 / eval num func2
Plus func1 func2 ->
eval num func1 + eval num func2
Minus func1 func2 ->
eval num func1 - eval num func2
-- Graph line drawing function
graphLine: Function -> Int -> Int -> Int -> String
graphLine func x ymin ymax =
let
-- value of f(x)
funcValue = round (eval (toFloat x) func)
-- number of points on the line
ySpan = abs ymin + abs ymax
in
-- Check if the value of f(x) is in the specified range
if (funcValue > ymin) && (funcValue < ymax) then
stringFill (funcValue - ymin) "*" ++ stringFill (ySpan - (funcValue - ymin)) "-"
else if (funcValue > ymin) then
stringFill ySpan "*"
else
stringFill ySpan "-"
-- Recursive function to create a string of specified characters with a given length
stringFill: Int -> String -> String
stringFill n sym =
if (n <= 0) then
""
else
sym ++ stringFill (n - 1) sym
-- xmin < xmax; ymin < ymax
graph: Function -> Int -> Int -> Int -> Int -> String
graph func xmin xmax ymin ymax =
-- Check if range is not possible
if xmin > xmax || ymin > ymax then
"Error: Range is negative"
else if xmin == xmax then
graphLine func xmin ymin ymax
else
graphLine func xmin ymin ymax ++ "\n" ++ graph func (xmin + 1) xmax ymin ymax
testPrint: Bool
testPrint = print (Plus (Mult (Plus (Const 3) X) (Minus X (Poly X 5))) (Const 2)) == "(((3 + x) * (x - (x ^ 5))) + 2)"
testEval: Bool
testEval = eval 2 (Plus (Mult (Plus (Const 3) X) (Minus X (Poly X 5))) (Const 2)) == -148
testGraph1: Bool
testGraph1 = graph (Plus (Minus (Poly (Minus (Div X (Const 5)) (Const 1)) 4) (Poly (Plus (Div X (Const -2)) (Const 2)) 2)) (Const 6)) -10 20 -10 10 ==
"********************\n********************\n********************\n*******************-\n**************------\n************--------\n**********----------\n**********----------\n***********---------\n************--------\n*************-------\n**************------\n***************-----\n****************----\n****************----\n****************----\n***************-----\n**************------\n************--------\n**********----------\n********------------\n******--------------\n****----------------\n**------------------\n*-------------------\n**------------------\n***-----------------\n*******-------------\n*************-------\n********************\n********************"
-- for reference 3x2-graph.png
testGraph2: Bool
testGraph2 = graph (Mult (Const 3) (Poly X 2)) -5 5 -1 10 == "***********\n***********\n***********\n***********\n****-------\n*----------\n****-------\n***********\n***********\n***********\n***********"
testEmptyParams: Bool
testEmptyParams = graph (Mult (Const 3) (Poly X 2)) 0 0 0 0 == ""
testSingleLine: Bool
testSingleLine = graph (Mult (Const 3) (Poly X 2)) 1 1 -1 10 == "****-------"
testInvalidArgs: Bool
testInvalidArgs = graph X 2 1 2 1 == "Error: Range is negative"
testAllGraphs : List Bool
testAllGraphs = [testGraph1, testGraph2, testEmptyParams, testSingleLine, testInvalidArgs]

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module Modelling2 exposing (..)
import Modelling1 exposing (..)
import HighOrder exposing (..)
{-
Modelling Math Functions (part 2)
Dimitar Byalkov and Kaloyan Stoykov
-}
f: Function
f = Plus (Mult (Plus (Const 3) X) (Minus X (Poly X 5))) (Const 2)
derivative: Function -> Function
derivative func =
case func of
-- constant
Const _ ->
Const 0
-- X
X ->
Const 1
-- sum
Plus left right ->
Plus (derivative left) (derivative right)
-- difference
Minus left right ->
Minus (derivative left) (derivative right)
-- product
Mult left right ->
Plus (Mult (derivative left) right) (Mult left (derivative right))
-- quotient
Div left right ->
Div (Minus (Mult (derivative left) right) (Mult left (derivative right)))
(Poly right 2)
-- power
Poly X right ->
Mult (Const right) (Poly X (right - 1))
Poly left right ->
Poly (derivative left) right
simplify: Function -> Function
simplify func =
-- tries to simplify until no further simplification is possible
repeatUntil (\x -> x == simplifyHelp x) simplifyHelp func
simplifyHelp: Function -> Function
simplifyHelp func =
case func of
-- arithmetics
Mult (Const left) (Const right) ->
Const (left * right)
Div (Const left) (Const right) ->
Const (left // right)
Plus (Const left) (Const right) ->
Const (left + right)
Minus (Const left) (Const right) ->
Const (left - right)
-- nested addition and subtraction
Poly left 1 ->
left
Poly _ 0 ->
(Const 1)
Poly (Const left) right ->
Const (left ^ right)
Poly left right ->
Poly left right
Mult (Const 1) right ->
right
Mult left (Const 1) ->
left
Mult _ (Const 0) ->
(Const 0)
Div (Const 0) _ ->
(Const 0)
Div left (Const 1) ->
left
Plus left (Const 0) ->
left
Plus (Const 0) right ->
right
Minus left (Const 0) ->
left
-- recursive simplification
Mult left right ->
Mult (simplify left) (simplify right)
Div left right ->
Div (simplify left) (simplify right)
Plus left right ->
Plus (simplify left) (simplify right)
Minus left right ->
Minus (simplify left) (simplify right)
_ ->
func