第2章MATLAB基本运算2.1数据类型2.1.1常数和变量例2-12.1.2整数和浮点数2.浮点数例2-2数据类型转换2.1.3复数例2-32.2矩阵和数组的算术运算2.2.1数组的创建Initializing（初始化）VariablesinMATLABInitializingVariablesinAssignmentStatements(赋值语句)Theexpressionsusedtoinitializearrayscanincludealgebraicoperations（代数运算）andallorportionsofpreviouslydefinedarrays.Forexample,theassignmentstatementsThesemicolon(;)attheendofeachassignmentstatementshownabovehasaspecialpurpose:例2-5例2-6:4.特殊矩阵和数组InitializingwithBuilt-inFunctions2.2.2数组的操作（2）单下标方式数组元素用单下标引用，就是先把数组的所有列按先左后右的次序连接成“一维长列”，然后对元素位置进行编号。以m×n的矩阵a为例，元素a(i,j)对应的单下标=(j-1)×m＋i。AccessingMultidimensionalArrayswithaSingleSubscript2.子矩阵的产生（Subarrays）子矩阵是从矩阵中取出其中一部分元素构成的。Foratwo-dimensionalarray,acolon(:)canbeusedinasubscripttoselectallofthevaluesofthatsubscript.Forexample,supposearr2=[123;-2-3-4;345];arr2(1,:)=arr2(:,1:2:3)=TheendFunctionIfendappearsindifferentsubscripts,itcanreturndifferentvalueswithinthesameexpression.Forexample,supposethatthe3×4arrayarr4isdefinedasfollows:>>arr4=[1234;5678;9101112]arr4=123456789101112arr4(2:end,2:end)=UsingSubarraysontheLeft-HandSideofanAssignmentStatementThenthefollowingassignmentstatementislegal,sincetheexpressionsonbothsidesoftheequalsignhavethesameshape(2×2):>>arr4(1:2,[14])=[2021;2223]arr4=2023212267239101112Notethatthearrayelements(1,1),(1,4),(2,1),and(2,4)wereupdated.AssigningaScalar（标量）toaSubarray:InitializingVariableswithKeyboardInput5．数组元素的删除2.2.3矩阵和数组函数2．数组翻转4．数据统计2.2.4矩阵和数组的算术运算矩阵运算符合线性代数规则eg：一般的数组和矩阵运算：运算符MATLAB形式含义Additiona+bArrayadditionandmatrixadditionSubtractiona–bArrayandmatrixsubtractionArrayMultiplicationa.*bElement-by-elementmultiplicationofaandb.MatrixMultiplicationa*bMatrixmultiplicationofaandb.ArrayRightDivisiona./bElement-by-elementdivisionofaandb:a(i,j)/b(i,j).ArrayLeftDivisiona.\bElement-by-elementdivisionofaandb,butwithbinthenumerator:b(i,j)/a(i,j).MatrixRightDivisiona/bMatrixdivisiondefinedbya*inv(b),whereinv(b)istheinverseofmatrixb.MatrixLeftDivisiona\bMatrixdivisiondefinedbyinv(a)*b,wherei