Matlab快速入门.docx

Matlab在科研中的应用浙江大学控制系2013年11月10日目 录IntroductionCurrent Directory BrowserEditor/DebuggerMatrices and Magic SquaresEntering MatricesYou can enter matrices into MATLAB in several different ways:Enter an explicit list of elements.Load matrices from external data files.Generate matrices using built-in functions.Create matrices with your own functions in M-files.A = 16 3 2 13; 5 10 11 8; 9 6 7 12; 4 15 14 1MATLAB displays the matrix you just entered.A =16 3 2 135 10 11 89 6 7 124 15 14 1sum, transpose, and diagsum(A)MATLAB replies withans =34 34 34 34Aans =16 5 9 43 10 6 152 11 7 1413 8 12 1sum(A)produces a column vector containing the row sumsans =34343434diag(A) %找对角线上的元素ans =161071sum(diag(A)ans =34fliplr(A) %左右翻转sum(diag(fliplr(A)ans =34A(1,4) + A(2,4) + A(3,4) + A(4,4)This producesans =34The Colon Operator %冒号操作符1:101 2 3 4 5 6 7 8 9 10To obtain nonunit spacing, specify an increment. For example,100:-7:50is100 93 86 79 72 65 58 51and0:pi/4:piis0 0.7854 1.5708 2.3562 3.1416A(1:k,j)is the first k elements of the jth column of A.sum(A(1:4,4)computes the sum of the fourth column.sum(A(:,end)sum(1:16)/4which, of course, isans =34The magic FunctionB = magic(4)B =16 2 3 135 11 10 89 7 6 124 14 15 1A = B(:,1 3 2 4) %每一行 与B相应的列对应A =16 3 2 135 10 11 89 6 7 124 15 14 1ExpressionsLike most other programming languages, MATLAB provides mathematicalexpressions, but unlike most programming languages, these expressionsinvolve entire matrices. The building blocks of expressions are:VariablesNumbersOperatorsFunctionsOperatorsExpressions use familiar arithmetic operators and precedence rules.+ Addition- Subtraction* Multiplication/ Division Left division (described in “Matrices and LinearAlgebra” in Using MATLAB) Power Complex conjugate transpose( ) Specify evaluation orderSeveral special functions provide values of useful constants.pi 3.14159265i Imaginary unit, -1j Same as ieps Floating-point relative precision, 2-52realmin Smallest floating-point number, 2-1022realmax Largest floating-point number, (2-e)21023Inf InfinityNaN Not-a-numbereps = 1.e-6clear epsWorking with MatricesGenerating Matriceszeros All zerosones All onesrand Uniformly distributed random elementsrandn Normally distributed random elementsZ = zeros(2,4)Z =0 0 0 00 0 0 0F = 5*ones(3,3)F =5 5 55 5 55 5 5N = fix(10*rand(1,10)N =4 9 4 4 8 5 2 6 8 0R = randn(4,4)R =1.0668 0.2944 -0.6918 -1.44100.0593 -1.3362 0.8580 0.5711-0.0956 0.7143 1.2540 -0.3999-0.8323 1.6236 -1.5937 0.6900The load Command16.0 3.0 2.0 13.05.0 10.0 11.0 8.09.0 6.0 7.0 12.04.0 15.0 14.0 1.0Store the file under the name magik.dat. Then the commandload magik.datAn easy way to read data into MATLAB in many text or binary formats is touse Import Wizard.M-FilesFor example, create a file containing these five lines.A = .16.0 3.0 2.0 13.05.0 10.0 11.0 8.09.0 6.0 7.0 12.04.0