1.第1章 MATLAB系统环境
1.1
注:plot函数为画图函数。例plot(x1,y1,':',x2,y2,'*');
1.2
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注:root为求根函数。p为方程变量前面系数矩阵。
1.3
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注:
2*x+3y-1*z = 2;
8*x+2*y+3*z = 4;
45*x+3*y+9*z = 23
求:x,y,z的值
注:inv为求逆函数。
1.4
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注:@(x)是匿名函数,这个x是可以被使用的,理解如下:
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2.第2章 MATLAB数据及其运算
2.1
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2.2
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注:rem(A,3)的结果如果为0,返回1,负责返回0。
2.3
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注:字符串可以像数组一样被应用。由于ch(k)=ch(k)-('a'-'A')结果为对应的ascci码值,所以后面要使用char函数,变回字符串。如下
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3. 第3章 MATLAB矩阵分析与处理
3.1
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注:magic(a),生成大大小为a*a的矩阵,并且行和列之和一样。
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3.2
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注:
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D*A,由线性代数知识可知,D的第一行乘以A的第一列放在第一个,依此类推。
3.3
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注:(1)b=[5,-2,6]',是行向量的转置变成列向量。
(2)inv函数为取逆函数。
补充:
(1)det函数为求矩阵行列式。
(2)rank函数为求矩阵的秩。
(3)trace函数为求矩阵的迹。
(4)norm函数为求矩阵范数。
(4)eig函数求矩阵的特征向量和特征值。
4.第4章 MATLAB程序流程控制
4.1
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法一:使用脚本
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法二:使用函数(调用函数时,用使用函数文件名)
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4.2
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注:使用input函数输入a,b,c的值,使用求根公式(-b+sqrt(b^2-4*a*C))/(2*a)求出根。
4.3
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4.4
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注:可以将所有的setstr换成char,一样的效果。
4.5
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注:在switch case语句中,如果case的值同时为多个时,使用元胞数组{}。
4.6
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注:fix为取整函数,rem为取余函数。
4.7
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法1:
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法2:
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注:将1~n放在一个变量里面变成行向量,同时对这个行向量进行操作。
4.8
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注:将整块面积分割成若干个小矩形。
4.9 *
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注:a为4*3的矩阵,k=a,k一次取一列,所以一共取3次。
4.10
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注:变量sum为所以数之和,sum/n是平均数。
4.11
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注:
(1)continue为跳过一次循环中的其他语句,进行下一次循环。
(2)break为跳出整个循环。
4.12
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4.13
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注:nargin为函数输入时的变量个数。
5.第5章 MATLAB绘图
5.1
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注:
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5.2
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5.3
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5.4
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5.5
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5.6
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注:plotyy函数可以将不同的量纲的函数放在统一坐标下。
5.7
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5.8
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注:subplot函数对窗口进行分割。
补充:
(1)
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(2)
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(3)
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(4)
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注;选项为stacked或grouped
(5)
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5.9
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注:给1为突出,给0为不突出
5.10
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5.11
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注:meshgrid画网格线
5.12
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5.13
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5.14
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6.第6章 MATLAB数据分析与多项式计算
6.1
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注:max函数为求最大值函数。max(a)求每一列的最大值,max(a,[],2)求每一行的最大值。
6.2
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6.3
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注:
(1)sum为求和函数,sum(a,1)为按列求和。sum(a,2)为按行求和。
(2)prod函数为求乘函数,用法与sum一样。
(3)mean函数为求平均值函数,用法与sum一样。
(4)cumsum函数为累加和函数,用法与sum一样。
(5)cumprod函数为累积和函数,用法和sum一样。
6.4
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6.5
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注
6.6
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注:corrcoef函数为求相关系数函数,
6.7
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注:sort为排序函数
6.8
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注:多项式加法时,前一项最高次和后一项最高次不同时,较低的需要将高次补0直到与前一项最高次相同,以便于计算。
6.9
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注:conv函数用于求多项式之间的乘积。
6.10
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注:deconv函数用于多项式之间的除法。
6.11
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注:polyder函数用于多项式的求导。
6.12
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注:polyval为代数多项式函数,求指定的x时的y值
补充:polyvalm函数为求代数矩阵多项式。与polyval不同的是:
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6.13
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注:
(1)roots为求多项式根函数
(2)roots求出来的值,带入poly函数可以求出原函数。
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6.14
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对比:结果与原函数差一个系数3。
6.15
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注:interp1为一维插值函数。
其中,X,Y为需要被插值函数的x和y,X1是你需要插值的点,method为你选择的插值方式:
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补充:interp2为二维插值函数,其插值模式与interp2一样。
6.16
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注:在指定点处插值
(1)interp2(x,y,Z,0.5,0.5),在(0.5,0.5)处插值
(2)interp2(x,y,Z,[0.5,0.6],0.4),在(0.5,0.4)和(0.6,0.4)处插值
(3)interp2(x,y,Z,[0.5,0.6],[0.4,0.5]),在(0.5,0.4)和(0.6,0.5)处插值
(4)interp2(x,y,Z,[0.5,0.6]',[0.4,0.5]),在(0.5,0.4)和(0.5,0.5)和(0.6,0.5)和(0.6,0.4)处插值。
找规律,当为两个大小相同的行向量时,一个行向量的x仅仅与另一个行向量的y值对应。当一个为行向量一个为列向量时,一个行向量的x值与另一个列向量的所有y对应。
6.17*
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注:这个的t和ti都为列向量都是因为需要编制二维模型,只有一个为u行向量一个为列向量时才可以实现,所以要取反。
6.18
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注:
(1)linspace(0,2*pi,50)等价于 0:50/pi:2*pi,用于创建数据
(2)polyfit为拟合函数,用于通过已知条件来预测给定点的值。