《高中数学程序框图课件新人教必修》由会员分享，可在线阅读，更多相关《高中数学程序框图课件新人教必修（26页珍藏版）》请在金锄头文库上搜索。
1、1.1.2 程序框图算法初步 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.复习1、算法的概念2、算法的特点3、常见的几个例子4、判断一个正整数是否是质数的算法Evaluation on
2、ly.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.算法的概念算法是指解决给定问题的有穷操作步骤的 描述，简单的说，算法就是解决问题的步 骤和方法。Evaluation only.Evaluation only. Cr
3、eated with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.算法的基本特点1、有穷性一个算法应包括有限的操作步骤，能在执行有穷 的操作步骤之后结束。2、确定性 算法的计算规则及相应的计算步骤必须是唯一确 定的，既不能含糊其词，也不能有二义性。3、可行性 算法中的每一个步
4、骤都是可以在有限的时间内完 成的基本操作，并能得到确定的结果 。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.程序框图又称流程图，是一种用程序框、流程线及文字 说明来表示算法的图形。程序
5、框名称功能终端框 （起止框 ）表示一个算法的起始和结束输入、 输出框表示算法的输入和输出的信 息处理框 （执行框 ）赋值、计算判断框判断一个条件是否成立，用 “是”、“否”或“Y”、“N”标明Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright
6、 2004-2011 Aspose Pty Ltd.判断一个正整数是否是质数的算法自然语言描述图形描述开始输入ni =2in-1或 r =0？求n除以i的余数ri 的值增加1，仍用i表示r =0？输出 “n不是质数”输出 “n是质数”结束是否是否S1：给定大于2的整数nS2：令i =2S3：用i 除n，得到余数rS4：判断“r =0”是否成立。若是，则n不是质数，结束算法；否则，将i 的值增加1，仍用i表示。S5：判断“i (n-1)”是否成立。若是，则n是质数，结束算法；否则，返回第三步。右图中的程序框图包含了哪些 逻辑结构？顺序结构循环结构条件结构Evaluation only.Evalu
7、ation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.例1 设计一算法：输入圆的半径,输出圆的面积，并画出流程图算法分析：第一步：输入圆的半径第二步：利用公式“圆的面积= 圆周率（半径的平方）”计算 圆的面积；第三步：输出圆的面积。开始
8、结束输入半径R计算S=Pi*R*R输出面积S定义Pi=3.14思考：整个程序框图有什么特点？Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.例2 已知一个三角形的三边长 分别为2,3,4,
9、利用海伦-秦九韶 公式设计一个算法,求出它的p=（2+3+4）/2s=SQR(p*(p2)*(p 3)*(p-4)输出s结束开始面积,画出算法的程序框图.海伦秦九韶公式： 已知三角形三边边长分别为 a, b, c，则三角形的面积为：其中Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 As
10、pose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.开始结束y=x2+x-2输出x , yx=3（1）阅读下面的程序框图，输出的结果是多少？练习巩固1（2）用程序框图描述算法：已知梯形两底边长分别为a、b，高为h，求梯形面积。 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copy
11、right 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.条件结构：步骤A满足条件？步骤B是否满足条件？步骤A是否 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright
12、2004-2011 Aspose Pty Ltd.例3：设计求x的算法，并画出程序框图表示。算法分析：第二步：若x0，则x= x第三步：若x0，则x=xx0？是否开始输入 x输出 x输出-x结束第一步：输入 x第四步：输出x的值Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose
13、 Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.例4 任意给定3 个正实数,设计 一个算法,判断 分别以这3个数 为三边边长的 三角形是否存 在.画出这个算 法的程序框图. 开始输入a，b，ca+bc，a+c b， b+c a是否同 时成立？存在这样的 三角形不存在这样 的三角形结束否是Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5
14、Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.练习巩固2 看下面的程序框图，分析算法的作用（1） 开始结束输入xy=3*x*x+4*x+5输出y（2）开始结束输入a,ba=60?credit=2credit=0否是S=(a+b)*0.5输出creditEvaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created
15、 with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.课堂作业开始输入aa 0输出 |a|=a输出 |a|=-a结束NY练习Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Cl
16、ient Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.开始X1=1X2=2m=(x1+x2)/2x2=mx1=mm*m 30|x1 x2|0.005(x1*x1 3)*(m*m 3) 0输出所求的近似值m结束m=(x1+x2)/2NyyN练习Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.Evaluation only.Evaluation only. C
