MATLAB基本输入输出.doc

1基本操作和简单语句输入1.1用函数sym定义符号矩阵例sym_matrixsymabcJackHelp_MeNO_WAY运行结果sym_matrixabcJackHelp_MeNO_WAY1.2用函数syms定义符号矩阵例symsabcM1symClassicalM2symJazzM3symBluesAabcM1M2M3sym235运行结果AabcClassicalJazzBlues2351.3矩阵的运算例1.A715256315B111222333A23运行结果:ans6取第二行第三列的值2.A715256315B111222333A:2运行结果:ans15取第二列的值13.A715256315B111222333A3:运行结果:ans315取第三行的值4.A715256315B111222333A:1:2:3运行结果:ans752635取第一列和第三列的值5.A715256315B111222333A:3.B:2运行结果:ans5126.A715256315B111222333A:3B2:运行结果:ans1010101212121010107A715256315B111222333AB运行结果:ans242424303030202020A、矩阵相乘.A715256315B111222333A.B运行结果ans7154101293159.A715256315A2运行结果:ans66176642337038134610.A715256315A.2运行结果:ans4912542536912511.A715256315B111222333B/A运行结果:ans0.18420.2105-0.23680.36840.4211-0.47370.55260.6316-0.710512.A715256315B111222333B./A运行结果:ans0.14291.00000.20001.00000.40000.33331.00003.00000.60001.4例输入C1:2:20步进为2C从1到20运行结果:C1357911131517191.5查找已创建的变量的信息删除无用的变量答1查找变量信息用whos在MATLAB里输入指令运行如下symsabcwhosa查看变量a的信息NameSizeBytesClassa1x1126symobjectGrandtotalis2elementsusing126bytes2删除变量用clear在MATLAB里输入指令运行如下图1删除前的变量运行cleara删除变量a图2删除后的变量2编程2.1编写程序计算123….2n1的值解程序如下functionsjiafanninput请输入n值:输入n值s0forI1:2:2n1i的步进为2直到2n1ssiends输出计算结果运行结果如下请输入n值:5令n5ans362.2分段函数编程存放在ff.m文件中解functionfffxifx0x1fxelseifx1xfff-3f0f2的值fff20.5f0.5858f∞的值fffInf无穷在MATLAB里表示方法为Inff03.矩阵计算3.1矩阵的创建1.加减法运算A111123136B816357492XABYA-B运行结果:A111123136B816357492XXAB92747105128YYA-B-70-5-2-3-4-3-642.乘法1.两个矩阵相乘例A23451221B011110001100XAB运行结果XXAB8563332矩阵的数乘例A23451221X2A运行结果XX2A4681024423向量的点乘维数相同的两个向量的点乘例A-102B-2-11XdotABYsumA.B两种表达方式运行结果一致运行结果X4Y44向量的叉乘例A123B456XcrossAB运行结果X-36-35混合积要注意的是先叉乘后点乘顺序不能颠倒例A123B456C-36-3XdotAcrossBC运行结果X543矩阵的除法例A123426749B412XAB‘’表示左除X是议程AXB的解运行的结果X-1.50002.00000.50004矩阵的乘方例A715256315A2运行结果:X6617664233703813465.矩阵的转置例A123456789BA矩阵转置的算法运行结果B1472583696.矩阵的逆矩阵1直接用逆矩阵的算法例A123221343XinvAYA-1矩阵的逆矩阵的两种算法运行结果X1.00003.0000-2.0000-1.5000-3.00002.50001.00001.0000-1.0000Y1.00003.0000-2.0000-1.5000-3.00002.50001.00001.0000-1.00002由增广矩阵进行初等行变换例A123100221010343001XrrefA