Mod for BDouble (#51)

* mod for BDouble

* Increase version number

* add precondition to mod

BigNumber.podspec

@@ -16,7 +16,7 @@ Pod::Spec.new do |s|
   #
 
   s.name         = "BigNumber"
-  s.version      = "2.1.1"
+  s.version      = "2.2.0"
   s.summary      = "A lightweight, high performance bignum library for Swift!"
 
   # This description is used to generate tags and improve search results.

Sources/Swift-Big-Number-Core.swift

@@ -2414,6 +2414,7 @@ public struct BDouble:
 		self.init(z, over: 1)
 	}
 
+	/// Warning: Due to the inprecision of Double beware that this might effect the precision of your BDouble
 	public init(_ d: Double)
 	{
 		let nStr = String(d)
@@ -2926,6 +2927,10 @@ public struct BDouble:
 	public static func /(lhs: BDouble, rhs: Double) -> BDouble { return lhs / BDouble(rhs) }
 	public static func /(lhs: BDouble, rhs: BInt) -> BDouble { return lhs / BDouble(rhs) }
 	public static func /(lhs: Double, rhs: BDouble) -> BDouble { return BDouble(lhs) / rhs }
+
+	public static func %(lhs: BDouble, rhs:BDouble) -> BDouble { return mod(lhs, rhs) }
+	public static func %(lhs: BDouble, rhs:Double) -> BDouble { return mod(lhs, BDouble(rhs)) }
+	public static func %(lhs: Double, rhs:BDouble) -> BDouble { return mod(BDouble(lhs), rhs) }
 
 	//
 	//
@@ -3138,3 +3143,13 @@ public func max(_ lhs: BDouble, _ rhs: BDouble) -> BDouble {
 	}
 	return rhs
 }
+
+/**
+ * Returns the modulo (remainder)
+ */
+public func mod(_ lhs: BDouble, _ rhs: BDouble) -> BDouble {
+	precondition(!rhs.isZero(), "Right hand side cannot be zero")
+	let inner_ceil: BDouble = -lhs/rhs
+	let _ceil: BDouble = BDouble(ceil(inner_ceil))
+	return lhs + (rhs*_ceil)
+}

Tests/BDoubleTests.swift

@@ -106,6 +106,21 @@ class BDoubleTests : XCTestCase {
 		}
 	}
 
+	func test_mod() {
+		let answers = [
+			("5.0", "2.6", "2.4"),
+			("10000.5234", "6.4774", "5.8952"),
+			("-108700.5234", "6.4774", "3.2034"),
+			("-1.5234", "6.4774", "4.954"),
+			("1.5234", "6.4774", "1.5234"),
+			("0", "1000", "0"),
+		]
+
+		for ans in answers {
+			XCTAssertEqual(mod(BDouble(ans.0)!, BDouble(ans.1)!), BDouble(ans.2)!)
+			XCTAssertEqual(BDouble(ans.0)! % BDouble(ans.1)!, BDouble(ans.2)!)
+		}
+	}
 
 	func testDecimalExpansionWithoutRounding()
 	{