东南大学Matlab作业2Word文件下载.docx
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ft）'
axis（[00.2-260260]）;
gridon;
2.Usingplottodisplaythefollowingvoltagewithappropriatelinetype,titleandlabels.Alsopresentthegraphwithsuitablerangesofaxis.
Inaddition,onthesamegraph,drawtheenvelopeoftheoscillationandaddlegends.
home_work_2_A_2.m
%lbsin-class-exercise1_22013/8/21
%functionUsingplottodisplaythefollowingvoltagewithappropriatelinetype,titleandlabels.Alsopresentthegraphwithsuitablerangesofaxis.
%v（t）=220exp（-5t）cos（2?
%Inaddition,onthesamegraph,drawtheenvelopeoftheoscillationandaddlegends.
clearall;
v=220*exp（-5*t）.*sin（2*pi*50*t）;
2）;
v（t）=220exp（-5t）cos（2?
holdon;
v1=220*exp（-5*t）;
plot（t,v1,'
b'
plot（t,-v1,'
holdoff;
legend（'
theoscillation'
theenvelopeoftheoscillation'
）;
axis（[01-220220]）;
3.Usesubplot,drawa2by2arrayofplotsforthefollowingfunctions:
Applyappropriatelinetype,title,labelsandaxisrangesforthegraphs.
home_work_2_A_3.m
%lbsin-class-exercise1_32013/8/21
%functionUsesubplot,drawa2by2arrayofplotsforthefollowingfunctions:
%v1=cos（10*pi*t）;
v2=exp（-5*t）.*v1;
v3=exp（-10*t）.*v1;
v4=exp（-20*t）.*cos（10*pi*t）
%Applyappropriatelinetype,title,labelsandaxisrangesforthegraphs.
v1=cos（10*pi*t）;
v2=exp（-5*t）.*v1;
v3=exp（-10*t）.*v1;
v4=exp（-20*t）.*cos（10*pi*t）;
subplot（2,2,1）
k'
v（t）=cos（10?
t）'
axis（[01-11]）
subplot（2,2,2）
plot（t,v2,'
r'
v（t）=exp（-5t）cos（10?
subplot（2,2,3）
plot（t,v3,'
g'
v（t）=exp（-10t）cos（10?
subplot（2,2,4）
plot（t,v4,'
v（t）=exp（-20t）cos（10?
4.Useplot3toplot2spiralcurveslikebelowwithappropriatelinewidthandcolour.
（1）home_work_2_A_4_1.m
0.01:
10;
x=sin（2*pi*t）.*exp（0.35*t-1）;
y=cos（2*pi*t）.*exp（0.35*t-1）;
z=0.25*t;
plot3（x,y,z,'
axis（[-1515-151503]）;
（2）home_work_2_A_4_2.m
x=1.5*t.*sin（2*pi*t）;
y=1.5*t.*cos（2*pi*t）;
z=0.2*t;
3）;
axis（[-1515-151502]）;
5.Displaythesurfaceusingmeshandcontourwithasuitableresolution:
home_work_2_A_5.m
[x,y]=meshgrid（0:
1:
100,0:
100）;
z=exp（-0.005.*（（x-50）.^2+（y-50）.^2））;
figure
（1）;
mesh（x,y,z）,xlabel（'
x'
）,ylabel（'
y'
）,gridon;
figure
（2）;
contour（x,y,z）,xlabel（'
6.Load2ofyourphotosintoMatlabWorkSpaceusingimread.a）Changebrightnesslocallyorglobally.b）Overlapthemtoproduceanewphoto.c）writeanewphotointoafileusingimwrite.（Note:
lowerversionofMatlabsuchas6.5isnotallowedtodosomedirectimageoperations.）
a）home_work_2_A_6_a.m
A=imread（'
lbs.jpg'
subplot（2,2,1）;
imshow（A）,title（'
初始图像'
size（A）;
subplot（2,2,2）;
B=histeq（A（:
:
1））;
%Enhancecontrastusinghistogramequalization.
imshow（B）,title（'
对比度增大处理'
subplot（2,2,3）;
C=imadjust（A,[0.3,0.7],[]）;
imshow（C）,title（'
亮度调节处理'
subplot（2,2,4）;
D=imfilter（A,2）;
imshow（D）,title（'
真彩色增强处理'
b）home_work_2_A_6_b.m
B=imread（'
man.jpg'
[M,N,L]=size（A）;
C（1:
M,1:
N,1:
L）=B（1:
L）;
imshow（A）;
figure1'
imshow（C）;
figure2'
figure（3）;
imshow（A+C）;
figure3'
c）home_work_2_A_6_c.m
B=imadjust（A,[0.2,0.6],[]）;
imwrite（B,'
lbs1.jpg'
imshow（'
7.Forlinearsimultaneousequations
theequationcoefficients:
A=[1-143
-545-6
07-89
-13-26];
（M=N）
a）FindthedeterminantofA,
b）FindtheinverseofAandcheckformatrixsingularity,
c）IfB=[5;
1;
-2;
3],findtheunknownxintheequation.
home_work_2_A_7.m
A=[1-143;
-545-6;
07-89;
disp（'
a）determinantofA'
det（A）
b）theinverseofAandcheckformatrixsingularity'
inv（A）
cond（A）
B=[5;
3]
c）thesolutionoftheequation'
x=inv（A）*B
result:
>
home_work_2_A_7
a）determinantofA
ans=
-765.0000
b）theinverseofAandcheckformatrixsingularity
0.3333-0.00000.3333-0.6667
0.20000.11760.2706-0.3882
0.20000.05880.0353-0.0941
0.0222-0.0392-0.06800.2183
16.4186
B=
5
1
-2
3
c）thesolutionoftheequation
x=
-1.0000
-0.5882
0.7059
0.8627
8.Forlinearsimultaneousequations,
M>
N,theequationcoefficients:
-13-26
1-253
147-3];
a）FindthedeterminantofA’*A,
b）FindtheinverseofA’*Aandcheckformatrixsingularity,
3;
4;
0],findthesolutionoftheequation.
home_work_2_A_8.m
-13-26;
1-253;
047-3];
a）determinantofA¡
¯
*A'
det（A'
*A）
b）theinverseofA¡
*Aandcheckformatrixsingularity'
inv（A'
cond（A'
0];
x=inv（A'
*A）*A'
*B
home_work_2_A_8
a）determinantofA’*A
2.1051e+07
b）theinverseofA’*Aandcheckformatrixsingularity
0.08840.0321-0.0013-0.0219
0.03210.02310.0002-0.0099
-0.00130.00020.00850.0053
-0.0219-0.00990.00530.0144
32.5278
-0.8903
-0.4898
0.5755
0.7083
9.Dataof10recordsareshownbelow
y=[3.54.33.75.46.67.38.78.89.49.010.012.011.39.913.3],
Usepolyfitwithdifferentorders（from1to3）ofpolynomialstofindacurveofbestfit.Checkthetotaldistancebetweenthefittedcurvezandrecordsdefinedby
.
home_work_2_A_9.m
x=1:
15;
y=[3.54.33.75.46.67.38.78.89.49.010.012.011.39.913.3];
plot（x,y,'
ro'
p=polyfit（x,y,1）;
z=polyval（p,x）;
plot（x,z,'
bx'
一阶拟合误差'
s1=sqrt（sum（（z-y）.^2））
p=polyfit（x,y,2）;
kx'
Linewidth'
1.5）;
二阶拟合误差'
s2=sqrt（sum（（z-y）.^2））
p=polyfit（x,y,3）;
r--'
linewidth'
point'
polyfit1'
polyfit2'
polyfit3'
三阶拟合误差'
s3=sqrt（sum（（z-y）.^2））
result：
home_work_2_A_9
一阶拟合误差
s1=
3.2807
二阶拟合误差
s2=
3.0399
三阶拟合误差
s3=
3.0398
10.Createasetof20pointsfromacurvebyMatlabcode:
20;
y=2*exp（-0.3*（x-5）.^2）+0.7*exp（-0.2*（x-12）.^2）;
Theninterpolatethecurveto60pointsusing‘linear’and‘spline’options,respectively.Seethequalityofdifferenttypesofinterpolation.
home_work_2_A_10.m
clearall,closeall;
xi=1:
1/3:
yi=interp1（x,y,xi,'
linear'
plot（xi,yi,'
b*'
spline'
m--'
PartB
1.Usingtheplotandsubplotfunctionscreate4plotsona2by2arrayofsubplots,forthefunctionexp（-t）sin（5t）showingineachplotthefunctioninthecorrespondingintervalsofti.e.（-2,-1）,（-1,0）,（0,1）and（1,2）.
home_work_2_B_1.m
t=-2:
-1;
v=exp（-t）.*sin（5*t）;
subplot（2,2,1）;
t=-1:
0;
t=1:
2;
2.Athreephaseinductionmotorcharacteristicisgivenintermsofmechanicalshaftoutputtorque
（NMNewton-meter）asafunctionofrotationalspeedω（rad/sradianpersecond）.Thisisapproximatedby3piece-wiselinearequationsasfollows:
Thismotorisdirectlycoupledtoaload
whichcanberepresentedas
Write2separateMatlabfunctionm-filesinwhich:
a）themotorcharacteristic,b）theloadcharacteristicaredefinedonlyasfunctionsofω.Namethemmotor.mandsysload.m,respectively.
a）motor.m
function[Tm]=motor（w）
fori=1:
length（w）;
ifw（i）>
=0&
w（i）<
=90*pi
Tm（i）=w（i）/（90*pi）+4.0;
elseifw（i）>
=90*pi&
=110*pi
Tm（i）=95*w（i）/（20*pi）-422.5;
elseif（w（i）>
=110*pi&
=120*pi）
Tm（i）=-10*w（i）/pi+1200;
end
end
motor（0）
4
w=0:
12*pi;
motor（w）
Columns1through10
4.00004.00354.00714.01064.01414.01774.02124.02484.02834.0318
Columns11through20
4.03544.03894.04244.04604.04954.05314.05664.06014.06374.0672
Columns21through30
4.07074.07434.07784.08134.08494.08844.0920
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