--- a/Fahad/Scala/Chapter5.sc Wed Jan 21 12:32:17 2015 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,107 +0,0 @@
-
-package greeter
-
-object Chapter5 {
- println("Welcome to the Scala worksheet") //> Welcome to the Scala worksheet
-
- /////////////////////////////////////////////////////////////////////////////
- // CHAPTER 5: FIRST-CLASS FUNCTIONS
-
- /*
- // Write a function to sumall integers between two given numbers a and b
- def sumInts(a: Int, b: Int): Int =
- if (a > b) 0 else a + sumInts(a + 1, b)
-
- sumInts(1, 5)
-
- //Write a function to sum the squares of all integers between two given numbers a and b
- def square(x: Int): Int = x * x
- def sumSquares(a: Int, b: Int): Int =
- if (a > b) 0 else square(a) + sumSquares(a + 1, b)
-
- square(5)
-
- //Write a function to sum the powers 2n of all integers n between two given numbers a and b:
- def powerOfTwo(x: Int): Int = if (x == 0) 1 else 2 * powerOfTwo(x - 1)
- def sumPowersOfTwo(a: Int, b: Int): Int =
- if (a > b) 0 else powerOfTwo(a) + sumPowersOfTwo(a + 1, b)
-
- sumPowersOfTwo(2, 4)
- */
-
- /*
- def sum(f: Int => Int, a: Int, b: Int): Int =
- if (a > b) 0 else f(a) + sum(f, a + 1, b)
-
- //def sumInts(a: Int, b: Int): Int = sum(id, a, b)
- //def sumInts(a: Int, b: Int): Int = sum((x: Int) => x, a, b)
- def sumInts(a: Int, b: Int): Int = sum(x => x, a, b)
- //def sumSquares(a: Int, b: Int): Int = sum(square, a, b)
- //def sumSquares(a: Int, b: Int): Int = sum((x: Int) => x * x, a, b)
- def sumSquares(a: Int, b: Int): Int = sum(x => x * x, a, b)
- def sumPowersOfTwo(a: Int, b: Int): Int = sum(powerOfTwo, a, b)
-
- def id(x: Int): Int = x
- def square(x: Int): Int = x * x
- */
- def powerOfTwo(x: Int): Int = if (x == 0) 1 else 2 * powerOfTwo(x - 1)
- //> powerOfTwo: (x: Int)Int
-
-
- // 5.2: Currying
-
- def sum(f: Int => Int): (Int, Int) => Int = {
- def sumF(a: Int, b: Int): Int =
- if (a > b) 0 else f(a) + sumF(a + 1, b)
- sumF
- } //> sum: (f: Int => Int)(Int, Int) => Int
-
- def sumInts = sum(x => x) //> sumInts: => (Int, Int) => Int
- def sumSquares = sum(x => x * x) //> sumSquares: => (Int, Int) => Int
- def sumPowersOfTwo = sum(powerOfTwo) //> sumPowersOfTwo: => (Int, Int) => Int
-
- sumSquares(1,10) + sumPowersOfTwo(10,20) //> res0: Int = 2096513
- sum(x => x * x)(2,4) //> res1: Int = 29
-
- // 5.3: Finding Fixed Points of Functions
-
- val tolerance = 0.001 //> tolerance : Double = 0.001
- def isCloseEnough(x: Double, y: Double) = Math.abs((x-y) / x) < tolerance
- //> isCloseEnough: (x: Double, y: Double)Boolean
- def fixedPoint(f: Double => Double)(firstGuess: Double) = {
- def iterate(guess: Double): Double = {
- val next = f(guess)
- if (isCloseEnough(guess, next)) next
- else iterate(next)
- }
- iterate(firstGuess)
- } //> fixedPoint: (f: Double => Double)(firstGuess: Double)Double
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-}