东南大学2015短学期MATLAB作业1.doc

Matlab Worksheet 1Part A1. Get into Matlab: Use the diary command to record your activity in to a file: diary mydiary01.doc before you start your work. (And diary off to switch off your diary when you finish your work.)At the Command Window assign a value x=10, then use the Up Key to repeat the expression, editing it to show the effect of using a semicolon after the 10, namely x=10;Answers: x=10x = 10 x=10;2. Confirm whether the following names of variables are acceptable:a) VelocityYes b) Velocity1Yes c) Velocity.1 Nod) Velocity_1Yes e) Velocity-01 Nof) velocityONEYes g) 1velocity No3. Assign two scalar variables x and y values x=1.5, y=2.3, then construct Matlab expressions for the following:a) b) c) d)Answers:10.2138，8.7566，0.0232，-3.73604. Assign two variables with complex values u=2+3j and v=4+10j and then construct expression for:a) b) c) d) Answers: a)0.3276 - 0.0690ib) -22.0000 +34.0000ic) 1.5000 - 1.0000id) 6.1421e+008 +1.5355e+009i5. Use the colon operator : to assign numerical values between 0 and 1 to vector array variable a in steps of 0.1.Answer: a=colon(0,0.1,1)6. Use linspace function to assign 20 values to vector variable y between 20 and 30.Answer: linspace(20,30,20)7. Assign 20 values to a variable h increasing logarithmically between 10 and 1000.Next, use the colon operator to assign the first 10 elements of h to a variable p.Answers: h=linspace(10,1000,20); p=h(1:10)8. Create 6 element row vector z with values 1.0 1.2 1.6 -1.7 1.8 1.9, then construct an expression for the sum of the 2nd 4th and 6th elements of z.Answers: z=1.0 1.2 1.6 -1.7 1.8 1.9sum=z(2)+z(4)+z(6)9. Use the colon operator to create a vector array x between 10 and -10in steps of -1, and second, an array vector y between 20 and -20 in steps -2 .a) Add x and y, b) subtract 10x from 5y.Answers: x=10:-1:-10y=20:-2:-20add=x+ysub=5*y-10*x10. Use the size, length, who and whos commands to establish the size and length of x and y from Question 9, and use transpose operator to convert vector x from Question 9.Answers: size(x)ans = 1 21 size(y)ans =21 whoYour variables are:add ans h p sub sum u v x y z whos Name Size Bytes Class add 1x21 168 double array ans 1x2 16 double array h 1x20 160 double array p 1x10 80 double array sub 1x21 168 double array sum 1x1 8 double array u 1x1 16 double array (complex) v 1x1 16 double array (complex) x 1x21 168 double array y 1x21 168 double array z 1x6 48 double arrayGrand total is 125 elements using 1016 bytes11. Show that if w= 2i 3i 3+i the . operator creates the transpose. What effect does the operator applied to w have on its own?Answer: w.ans = 0 + 2.0000i 0 + 3.0000i 3.0000 + 1.0000iwans = 0 - 2.0000i 0 - 3.0000i 3.0000 - 1.0000i 12. Use the ones function to create a 4 by 6 array of 1s. Considering just the shape of the resulting array, what do the expression ones(3), ones(5) and ones(7) all have in common?Answer:ones(4,6)They are all N-by-N matrix of ones.13. Create using the rand function a 5 by 4 random matrix and assign it to matrix array variable A and observe carefully what A(:,3) A(1:2) and A(3,2 4) mean.Answer: A=rand(5,4)A = 0.0579 0.2028 0.0153 0.4186 0.3529 0.1987 0.7468 0.8462 0.8132 0.6038 0.4451 0.5252 0.0099 0.2722 0.9318 0.20260.1389 0.1988 0.4660 0.6721A(:,3)ans = 0.0153 0.7468 0.4451 0.9318 0.4660A(1:2)ans = 0.0579 0.3529A(3,2 4) ans = 0.6038 0.525214. Using array subscripts, create an expression for the sum of the element in the top right-hand-corner of A and the bottom left-hand-corner of A. Also assign the 2nd column of A to a column vector b, and assign the 3rd row of A to a row vector d.Answer: sum=A(4,1)+A(1,4)sum =0.4285b=A(:,2)b = 0.2028 0.1987 0.6038 0.2722 0.1988d=A(3,:)d = 0.8132 0.6038 0.4451 0.5252 diary off to switch off your diary now.15. Using the colon operator, assign a row vector array t, values between 0 and 10 in steps of 0.01. Use the ; operator to prevent displaying the information. Obtain the term-by-term values of functions:a) b) c) Answers:a) z=exp(-0.05*t);b) z=exp(-0.05*t).*sin(pi*t);c) z=exp(-0.05*t).*sin(pi*t).*cos(2*pi*t);16. For Question 15 c), use the plot function to plot the value z against t. And use xlabel and ylabel to label the t axis time and z axis Response and use title to give your figure a title. Copy the figure into your mydiary01.doc (from the figure edit menu, select copy, then open mydiary01.doc and paste in the figure as an object).Answers: Part B1. Create a new Script m-file, called myfirst.m, to assign values to three vector arrays a, b, and c; add each component together and assign to array d, where A= 1, 2, 3, b=4 5 6, c=7 8 9. Run myfirst.m. Examine the variable values in the WorkSpace . Edit myfirst.m to change variable b to b=10 20 30. Re-run myfirst.mAnswers:d =12 15 18d = 18 30 422. Create a function m-file, called myfun.m, that accepts two arrays x and y as arguments, and produces the sum of x and y, and gives as the function output, the maximum of x+y.Answer:x=1 2 3 ;y=2 3 4 ; myfun(x,y)ans = 3 5 7min(myfun(x,y)ans = 33. Modify your script m-file myfirst.m by calling in it myfun.m twice, namely with a and b as parameters in the argument list, and second with parameters b and c. Run myfirst.mand afterwards. Examine the WorkSpace variable values.Answers:myfirst.fun:clear all;a= 1, 2, 3;b=10 20 30; c=7 8 9;aplusb=myfun(a,b);bplusc=myfun(b,c)Command Window:aplusb = 11 22 33 bpluscbplusc = 17 28 394. Modify your script m-file myfirst.m by introducing variables A and B. Assign scalar values A=1, B=2. Declare A and B as global variables both in myfirst.m and myfun.m. Modify myfun.m by adding A and B to the maximum value of x+y. Answers:myfirst.m:global Aglobal BA=1;B=2;myfun.m:function sumA, sumB = myfun(x, y)global A;global B;sumA=A+max(x+y);sumB=B+max(x+y);Command Window:x=1 2 3;y=2 3 4 ;a,b=myfun(x,y)a = 8b = 95. Create a script m-file and, using a pair of nested for loops, assign to a 5 by 5 matrix array A, values equal to the sum of the subscripts. Ensure that the array is first cleared before the loops and afterwards display the array values. Run the m-file.Answer: m-file:clear allfor m=1:5 for n=1:5 A(m,n)=m+n; endendACommand Window:A = 2 3 4 5 6 3 4 5 6 7 4 5 6 7 8 5 6 7 8 9 6 7 8 9 106. Relational Operators:- Assign variables x=1 and y=2, then examine the values of the expressions:a) xy, b)xy)*(x=y)?Answer: a) ans = 0b) ans = 1c)ans = 2z = 07. While loop:- Create a script m-file, and using a while loop, generate the partial sum for the series: which stops adding-on terms when they are less than 1e-6 times the total sum.Answer: m-file:clear allterm =1/pi;n=1;sum=term;while (term 1e-6*sum) n=n+1; term=term/n; sum = sum + term;endsumCommand Window:sum = 0.54698. While loop:- Use a while loop to keep adding array A to itself until just one of the elements in A is greater than, but not equal to 40 where, initially .Answer: m-file:A=1 2; 3 4;while (max(max(A) y) a=x;else a=y;endCommand Window: new(1,1)ans = 110. If statements:- Create a function m-file that receives variable x, y and z as arguments, then uses an if elseif and else statements, generate the output value to be =x if first of all x1, otherwise =y if y10, otherwise =z if z20, otherwise =1 if none of those conditions hold. Test it on values (100,100,100) and (0, 0,0).Answer:m-file:function a = new (x, y,z)if (x 1) a=x;elseif(y 10) a=y;elseif(z 20) a=z;else a=1;endCommand Window: new(100,100,100)ans = 100 new(0,0,0)ans = 111. Switch Statement:- Create a function with one input argument x to test whether the expression: real(x2) is equal to 0,1, or -1, which then displays a string stating appropriately whether: x is equal to zero, x is equal to +1 or -1 or x