swift演算法手記-5

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////  ViewController.swift//  learn5////  Created by myhaspl on 16/1/23.//  Copyright (c) 2016年 myhaspl. All rights reserved.//import Cocoaimport Foundationclass ViewController: NSViewController {    override func viewDidLoad() {        super.viewDidLoad()        // Do any additional setup after loading the view.    }    override var representedObject: AnyObject?
 {        didSet {        // Update the view, if already loaded.        }    }private func comresult(inputnum:Double)->Double{        //  5*x^7-3*x^5+16*x^2+7*x+90=0        let myresult:Double = 5 * pow(inputnum,7) - 3 * pow(inputnum,5) + 16 * pow(inputnum,2) + 7 * inputnum + 90        return myresult}    @IBOutlet weak var result: NSTextField!        @IBAction func compute(sender: AnyObject){//  5*x^7-3*x^5+16*x^2+7*x+90=0//  二分法求一元方程的解,最大求解範圍[-100000,100000]      let trycount = 80      var accuracy: Double = 0.00000000000001      var answer: Double?
=nil     // 預計解範圍      var leftbound:Double?=nil  var rightbound:Double?=nil        for var bound:Double=1;bound<10000000;bound*=10{  let leftres=comresult(-bound)  let rightres=comresult(bound)      if  (leftres*rightres) < 0 {  leftbound = (-bound)  rightbound = bound  break  }  }  if (leftbound==nil || rightbound==nil){  return   }  //計算方程的解  for i in 1...trycount{                result.stringValue=String(i)        let center=leftbound!+(rightbound!-leftbound!)/2let leftres:Double=comresult(leftbound!)        let rightres:Double=comresult(rightbound!)let centres:Double=comresult(center)if centres==0 {answer=centerbreak}else if abs(rightbound!-leftbound!) < accuracy {answer=leftbound!break}else if leftres*centres<0{rightbound=center}else if rightres*centres<0{leftbound=center}  }    if let ans=answer{//方程有解 result.stringValue="解："+String(stringInterpolationSegment: ans)+"   "         result.stringValue += "解代入方程的值："+String(stringInterpolationSegment:comresult(ans))  }         }}

本部落格全部內容是原創。假設轉載請註明來源http://blog.csdn.net/myhaspl/

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swift演算法手記-5