MATLAB编程练习(含答案很好的)

001双峰曲线图：
z=peaks(40);
mesh(z);
surf(z)
002解方程：
A=[3,4,-2;6,2,-3;45,5,4];
>> B=[14;4;23];
>> root=inv(A)*B
003傅里叶变换
load mtlb ;
subplot(2,1,1);
plot(mtlb);
>> title('原始语音信息');
>> y=fft(mtlb);
>> subplot(2,1,2);
>> yy=abs(y);
>> plot(yy);
>> title('傅里叶变换')
004输入函数：
a=input('How many apples\n','s')
005输出函数
a=[1 2 3 4 ;5 6 7 8;12 23 34 45;34 435 23 34]
a =
1 2 3 4
5 6 7 8
12 23 34 45
34 435 23 34
disp(a)
a =
1 2 3 4
5 6 7 8
12 23 34 45
34 435 23 34
b=input('how many people\n' ,'s')
how many people
two people
b =
two people
>> disp(b)
two people
>>
006求一元二次方程的根
a=1;b=2;c=3;
d=sqrt(b^2-4*a*c);
x1=(-b+d)/(2*a)
x1 =
-1.0000 + 1.4142i
>> x2=(-b-d)/(2*a)
x2 =
-1.0000 - 1.4142i
007求矩阵的相乘、转置、存盘、读入数据A=[1 3 5 ;2 4 6;-1 0 -2;-3 0 0];
>> B=[-1 3;-2 2;2 1];
>> C=A*B
C =
3 14
2 20
-3 -5
3 -9
>> C=C'
C =
3 2 -3 3
14 20 -5 -9
>> save mydat C
>> clear
>> load mydat C
008编写数学计算公式：
A=2.1;B=-4.5;C=6;D=3.5;E=-5;
K=atan(((2*pi*A)+E/(2*pi*B*C))/D) K =
1.3121
009
A=[1 0 -1;2 4 1;-2 0 5];
>> B=[0 -1 0;2 1 3;1 1 2];
>> H=2*A+B
H =
2 -1 -2
6 9 5
-3 1 12
>> M=A^2-3*B
M =
3 3 -6
2 1
3 -2
-15 -3 21
>> Y=A*B
Y =
-1 -2 -2
9 3 14
5 7 10
>> R=B*A
R =
-2 -4 -1
-2 4 14
-1 4 10
>> E=A.*B
E =
0 0 0
4 4 3
-2 0 10
>> W=A\B
W =
0.3333 -1.3333 0.6667
0.2500 1.0000 0.2500
0.3333 -0.3333 0.6667 >> P=A/B
P =
-2.0000 3.0000 -5.0000
-5.0000 3.0000 -4.0000
7.0000 -9.0000 16.0000
>> Z=A.\B
Warning: Divide by zero.
Z =
0 -Inf 0
1.0000 0.2500 3.0000
-0.5000 Inf 0.4000
>> D=A./B
Warning: Divide by zero.
D =
Inf 0 -Inf
1.0000 4.0000 0.3333
-2.0000 0 2.5000
010
a=4.96;b=8.11;
>> M=exp(a+b)/log10(a+b)
M =
4.2507e+005
011求三角形面积：
a=9.6;b=13.7;c=19.4;
>> s=(a+b+c)/2;
>> area=sqrt(s*(s-a)*(s-b)*(s-c))
area =
61.1739
012逻辑运算
A=[-1 0 -6 8;-9 4 0 12.3;0 0 -5.1 -2;0 -23 0 -7]; >> B=A(:,1:2)
B =
-1 0
-9 4
0 0
0 -23
>> C=A(1:2,:)
C =
-1.0000 0 -6.0000 8.0000 -9.0000 4.0000 0 12.3000
>> D=B'
D =
-1 -9 0 0
0 4 0 -23
>> A*B
ans =
1.0000 -184.0000
-27.0000 -266.9000
0 46.0000 207.0000 69.0000
>> C<D
ans =
0 0 1 0
1 0 0 0
>> C&D
ans =
1 0 0 0
0 1 0 1
>> C|D
ans =
1 1 1 1
1 1 0 1
>> ~C|~D
ans =
0 1 1 1
1 0 1 0
013矩阵运算练习：
A=[8 9 5;36 -7 11;21 -8 5]
A =
8 9 5
36 -7 11
21 -8 5
>> B
B =
-1 3 -2
2 0 3
-3 1 9
>> RT=A*B
RT =
-5 29 56
-83 119 6
-52 68 -21
>> QW=A.*B
QW =
-8 27 -10
72 0 33
-63 -8 45
>> ER=A^3
ER =
6272 3342 2944
15714 -856 5260
8142 -1906 2390 >> BF=A.^3
BF =
512 729 125
46656 -343 1331
9261 -512 125 >> A/B
ans =
3.1341
4.9634 -0.4024
-1.2561 12.5244 -3.2317
-1.9878 6.4512 -2.0366
>> EKV=B\A
EKV =
10.7195 -1.2683 3.5244
9.4756 1.5854 3.7195
4.8537 -1.4878 1.3171
>> KDK=[A,B]
KDK =
8 9 5 -1 3 -2
36 -7 11 2 0 3
21 -8 5 -3 1 9 >> ERI=[A;B]
ERI =
8 9 5
36 -7 11
21 -8 5
-1 3 -2
2 0 3
-3 1 9
014一般函数的调用：
A=[2 34 88 390 848 939];
>> S=sum(A)
S =
2301
>> min(A)
ans =
2
>> EE=mean(A)
EE =
383.5000
>> QQ=std(A)
QQ =
419.3794
>> AO=sort(A)
AO =
2 34 88 390 848 939 >> yr=norm(A)
yr =
1.3273e+003
>> RT=prod(A)
RT =
1.8583e+012
>> gradient(A)
ans =
32.0000 43.0000 178.0000 380.0000 274.5000 91.0000 >> max(A)
ans =
939
>> median(A)
ans =
239
>> diff(A)
ans =
32 54 302 458 91
>> length(A)
ans =
6
>> sum(A)
ans =
2301
>> cov(A)
ans =
1.7588e+005
>>
015矩阵变换：
A=[34 44 23;8 34 23;34 55 2]
A =
34 44 23
8 34 23
34 55 2
>> tril(A)
ans =
34 0 0
8 34 0
34 55 2
>> triu(A)
ans =
34 44 23
0 34 23
0 0 2
>> diag(A)
ans =
34
34
2
norm(A)
ans =
94.5106
>> rank(A)
ans =
3
>> det(A)
ans =
-23462
>> trace(A)
ans =
70
>> null(A)
ans =
Empty matrix: 3-by-0
>> eig(A)
ans =
80.1587
12.7671
-22.9257
>> poly(A)
ans =
1.0e+004 *
0.0001 -0.0070 -0.1107 2.3462
>> logm(A)
Warning: Principal matrix logarithm is not defined for A with nonpositive real eigenvalues. A non-principal matrix
logarithm is returned.
> In funm at 153
In logm at 27
ans =
3.1909 + 0.1314i 1.2707 + 0.1437i 0.5011 - 0.2538i
0.4648 + 0.4974i 3.3955 + 0.5438i 0.1504 - 0.9608i
0.2935 - 1.2769i 0.8069 - 1.3960i 3.4768 + 2.4663i
>> fumn(A)
Undefined command/function 'fumn'.
>> inv(A)
ans =
0.0510 -0.0502 -0.0098
-0.0326 0.0304 0.0255
0.0305 0.0159 -0.0343
>> cond(A)
ans =
8.5072
>> chol(A)
Error using ==> chol
Matrix must be positive definite.
>> lu(A)
ans =
34.0000 44.0000 23.0000
0.2353 23.6471 17.5882
1.0000 0.4652 -29.1816
>> pinv(A)
ans =
0.0510 -0.0502 -0.0098
-0.0326 0.0304 0.0255
0.0305 0.0159 -0.0343
>> svd(A)
ans =
94.5106
22.3456
11.1095
>> expm(A)
ans =
1.0e+034 *
2.1897 4.3968 1.9382
1.3154
2.6412 1.1643
1.8782 3.7712 1.6625
>> sqrtm(A)
ans =
5.2379 + 0.2003i 3.4795 + 0.2190i 1.8946 - 0.3869i
0.5241 + 0.7581i 5.1429 + 0.8288i 2.0575 - 1.4644i
3.0084 - 1.9461i
4.7123 - 2.1276i 2.1454 + 3.7589i >>
016多项式的计算：
A=[34 44 23;8 34 23;34 55 2]
A =
34 44 23
8 34 23
34 55 2
>> P=poly(A)
P =
1.0e+004 *
0.0001 -0.0070 -0.1107 2.3462
>> PPA=poly2str(P,'X')
PPA =
X^3 - 70 X^2 - 1107 X + 23462
017多项式的运算：
p=[2 6 8 3];w=[32 56 0 2];
>> m=conv(p,w)
m =
64 304 592 548 180 16 6 >> [q,r]=deconv(w,p)
q =
16
r =
0 -40 -128 -46
>> dp=polyder(w)
dp =
96 112 0
>> [num,den]=polyder(w,p)
num =
80 512 724 312 -16
den =
4 24 68 108 100 48 9
>> b=polyfit(p,w,4)
Warning: Polynomial is not unique; degree >= number of data points. > In polyfit at 74
b =
-0.6704 9.2037 -32.2593 0 98.1333
>> r=roots(p)
r =
-1.2119 + 1.0652i
-1.2119 - 1.0652i
-0.5761
018求多项式的商和余
p=conv([1 0 2],conv([1 4],[1 1]))
p =
1 5 6 10 8
>> q=[1 0 1 1]
q =
1 0 1 1
>> [w,m]=deconv(p,q)
w =
1 5
m =
0 0 5 4 3
>> cq=w;cr=m;
>> disp([cr,poly2str(m,'x')])
5 x^2 + 4 x + 3
>> disp([cq,poly2str(w,'x')])
x + 5
019将分式分解
a=[1 5 6];b=[1];
>> [r,p,k]=residue(b,a)
r =
-1.0000
1.0000
p =
-3.0000
-2.0000
k =
[]
020计算多项式：
a=[1 2 3;4 5 6;7 8 9];
>> p=[3 0 2 3];
>> q=[2 3];
>> x=2;
>> r=roots(p)
r =
0.3911 + 1.0609i
0.3911 - 1.0609i
-0.7822
>> p1=conv(p,q)
p1 =
6 9 4 12 9
>> p2=poly(a)
p2 =
1.0000 -15.0000 -18.0000 -0.0000 >> p3=polyder(p)
p3 =
9 0 2
>> p4=polyval(p,x)
p4 =
31
021求除式和余项：
[q,r]=deconv(conv([1 0 2],[1 4]),[1 1 1])
022字符串的书写格式：
s='student'
s =
student
>> name='mary';
>> s1=[name s]
s1 =
marystudent
>> s3=[name blanks(3);s]
s3 =
mary
student
>>
023交换两个数：
clear
clc
a=[1 2 3 4 5];
b=[6 7 8 9 10];
c=a;
a=b;
b=c;
a
b
24If语句
n=input('enter a number,n=');
if n<10
n
end
025 if 双分支结构
a=input('enter a number ,a=');
b=input('enter a number ,b=');
if a>b
max=a;
else
max=b;
end
max
026三个数按照由大到小的顺序排列：A=15;B=24;C=45;
if A<B
T=A;A=B;B=T;
elseif A<C
T=A;A=C;C=T;
elseif B<C
T=B;B=C;C=T;
end
A
B
C
027建立一个收费优惠系统：
price=input('please jinput the price : price=') switch fix(price/100)
case[0,1]
rate =0;
case[2,3,4]
rate =3/100;
case num2cell(5:9)
rate=5/100;
case num2cell(10:24)
rate=8/100;
case num2cell(25:49)
rate=10/100;
otherwise
rate=14/100;
end
price=price*(1-rate)
028：while循环语句
i=0;s=0;
while i<=1212
s=s+i;
i=i+1;
end
s
029，用for循环体语句：
sum=0;
for i=1:1.5:100;
sum=sum+i;
end
sum
030循环的嵌套
s=0;
for i=1:1:6;
for j=1:1:8;
s=s+i^j;
end;
end;
s
031continue 语句的使用：
for i=100:120;
if rem(i,7)~=0;
continue;
end;
i
end
032
x=input ('输入X的值x=')
if x<1
y=x^2;
elseif x>1&x<2
y=x^2-1;
else
y=x^2-2*x+1;
end
y
033求阶乘的累加和
sum=0;
temp=1;
for n=1:10;
temp=temp*n;
sum=sum+temp;
end
sum
034对角线元素之和
sum=0;
a=[1 2 3 4;5 6 7 8;9 10 11 12;13 14 15 16]; for i=1:4;
sum=sum+a(i,i);
end
sum
035用拟合点绘图
A=[12 15.3 16 18 25];
B=[50 80 118 125 150.8];
plot(A,B)
036绘制正玄曲线：
x=0:0.05:4*pi;
y=sin(x);
plot(x,y)
037绘制向量
x=[1 2 3 4 5 6;7 8 9 10 11 12;13 14 15 16 17 18] plot(x)
x=[0 0.2 0.5 0.7 0.6 0.7 1.2 1.5 1.6 1.9 2.3]
plot(x)
x=0:0.2:2*pi
y=sin(x)
plot(x,y,'m:p')
038在正弦函数上加标注：
t=0:0.05:2*pi;
plot(t,sin(t))
set(gca,'xtick',[0 1.4 3.14 56.28])
xlabel('t(deg)')
ylabel('magnitude(v)')
title('this is a example ()\rightarrow 2\pi')
text(3.14,sin(3.14),'\leftarrow this zero for\pi')
039添加线条标注
x=0:0.2:12;
plot(x,sin(x),'-',x,1.5*cos(x),':');
legend('First','Second',1)
040使用hold on 函数
x=0:0.2:12;
plot(x,sin(x),'-');
hold on
plot(x,1.5*cos(x),':');
041一界面多幅图
x=0:0.05:7;
y1=sin(x);
y2=1.5*cos(x);
y3=sin(2*x);
y4=5*cos(2*x);
subplot(221);plot(x,y1);title('sin(x)')
subplot(222);plot(x,y2);title('cos(x)')
subplot(223);plot(x,y3);title('sin(2x)')
subplot(224);plot(x,y4);title('cos(2x)')
042染色效果图
x=0:0.05:7;
y1=sin(x);
y2=1.5*cos(x);
y3=sin(2*x);
y4=5*cos(2*x);
subplot(221);plot(x,y1);title('sin(x)');fill(x,y1,'r') subplot(222);plot(x,y2);title('cos(x)');fill(x,y2,'b') subplot(223);plot(x,y3);title('sin(2x)');fill(x,y3,'k') subplot(224);plot(x,y4);title('cos(2x)');fill(x,y4,'g')
043特殊坐标图
clc
y=[0,0.55,2.5,6.1,8.5,12.1,14.6,17,20,22,22.1] subplot(221);plot(y);
title('线性坐标图');
subplot(222);semilogx(y);
title('x轴对数坐标图');
subplot(223);semilogx(y);
title('y轴对数坐标图');
subplot(224);loglog(y);
title('双对数坐标图')
t=0:0.01:2*pi;
r=2*cos(2*(t-pi/8));
polar(t,r)
044特殊函数绘图：
fplot('cos(tan(pi*x))',[-0.4,1.4])
fplot('sin(exp(pi*x))',[-0.4,1.4])
045饼形图与条形图：
x=[8 20 36 24 12];
subplot(221);pie(x,[1 0 0 0 1]);
title('饼图');
subplot(222);bar(x,'group');
title('垂直条形图');
subplot(223);bar(x,'stack');
title('累加值为纵坐标的垂直条形图'); subplot(224);barh(x,'group');
title('水平条形图');
046梯形图与正弦函数
x=0:0.1:10;
y=sin(x);
subplot(121);stairs(x);
subplot(122);stairs(x,y);
047概率图
x=randn(1,1000);
y=-2:0.1:2;
hist(x,y)
048向量图：
x=[-2+3j,3+4j,1-7j];
subplot(121);compass(x);
rea=[-2 3 1];
imag=[3 4 -7];
subplot(122);feather(rea,imag);
049绘制三维曲线图：
z=0:pi/50:10*pi;
x=sin(z);
y=cos(z);
plot3(x,y,z)
x=-10:0.5:10;
y=-8:0.5:8;
[x,y]=meshgrid(x,y);
z=sin(sqrt(x.^2+y.^2))./sqrt(x.^2+y.^2); subplot(221);
mesh(x,y,z);
title('普通一维网格曲面');
subplot(222);
meshc(x,y,z);
title('带等高线的三维网格曲面'); subplot(223);
meshz(x,y,z);
title('带底座的三维网格曲面'); subplot(224);
surf(x,y,z);
title('充填颜色的三维网格面')
050 带网格二维图
x=0:pi/10:2*pi;
y1=sin(x);
y2=cos(x);
plot(x,y1,'r+-',x,y2,'k*:')
grid on
xlabel('Independent Variable x') ylabel('Dependent Variable y1&y2') text(1.5,0.5,'cos(x)')
051各种统计图
y=[18 5 28 17;24 12 36 14;15 6 30 9]; subplot(221);bar(y)
x=[4,6,8];
subplot(222);bar3(x,y)
subplot(223);bar(x,y,'grouped') subplot(224);bar(x,y,'stack')
052曲面图
x=-2:0.4:2;
y=-1:0.2:1;
[x,y]=meshgrid(x,y);
z=sqrt(4-x.^2/9-y.^2/4); surf(x,y,z)
grid on
053创建符号矩阵
e=[1 3 5;2 4 6;7 9 11];
m=sym(e)
符号表达式的计算问题
因式分解：
syms x
f=factor(x^3-1)
s=sym('sin(a+b)'); expand(s)
syms x t
f=x*(x*(x-8)+6)*t; collect(f)
syms x
f=sin(x)^2+cos(x)^2; simplify(f)
syms x
s=(4*x^2+8*x+3)/(2*x+1); simplify(s)
通分
syms x y
f=x/y-y/x;
[m,n]=numden(f)
嵌套重写
syms x
f=x^4+3*x^3-7*x^2+12; horner(f)
054求极限
syms x a;
limit(exp(-x),x,0,'left')
求导数
syms x
diff(x^9+x^6)
diff(x^9+x^6,4)
055求不定积分与定积分syms x y
s=(4-3*x^2)^2;
int(s)
int(x/(x+y),x)
int(x^2/(x+2),x,1,3) double(ans)
056函数的变换：
syms x t
y=exp(-x^2);
Ft=fourier(y,x,t)
fx=ifourier(Ft,t,x)
057求解方程
syms a b c x
s=a*x^2+b*x+c;
solve(s)
syms x y z
s1=2*x^2+y^2-3*z-4;
s2=y+z-3;
s3=x-2*y-3*z;
[x,y,z]=solve(s1,s2,s3)
058求微分方程：
y=dsolve('Dy-(t^2+y^2)/t^2/2','t')
059求级数和
syms x k
symsum(k)
symsum(k^2-3,0,10)
symsum(x^k/k,k,1,inf)
060泰勒展开式
syms x
s=(1-x+x^2)/(1+x+x^2);
taylor(s)
taylor(s,9)
taylor(s,x,12)
taylor(s,x,12,5)
061练习
syms x a;
s1=sin(2*x)/sin(5*x);
limit(s1,x,0)
s2=(1+1/x)^(2*x);
limit(s2,x,inf)
syms x
s=x*cos(x);
diff(s)
diff(s,2)
diff(s,12)
syms x
s1=x^4/(1+x^2);
int(s1)
s2=3*x^2-x+1
int(s2,0,2)
syms x y z
s1=5*x+6*y+7*z-16;
s2=4*x-5*y+z-7;
s3=x+y+2*z-2;
[x,y,z]=solve(s1,s2,s3)
syms x y
y=dsolve('Dy=exp(2*x-y)','x')
y=dsolve('Dy=exp(2*x-y)','y(0)=0','x')
n=sym('n');
s=symsum(1/n^2,n,1,inf)
x=sym('x');
f=sqrt(1-2*x+x^3)-(1-3*x+x^2)^(1/3);
taylor(f,6)
062求于矩阵相关的值
a=[2 2 -1 1;4 3 -1 2;8 5 -3 4;3 3 -2 2]
adet=det(a)
atrace=trace(a)
anorm=norm(a)
acond=cond(a)
arank=rank(a)
eiga=eig(a)
063矩阵计算
A=[0.1389 0.6038 0.0153 0.9318;0.2028 0.2772 0.7468 0.4660;0.1987 0.1988 0.4451 0.4186]
B=var(A)
C=std(A)
D=range(A)
E=cov(A)
F=corrcoef(A)
064求根及求代数式的值
P=[4 -3 2 5];
x=roots(P)
x=[3 3.6];
F=polyval(P,x)
065多项式的和差积商运算：
f=[1 2 -4 3 -1]
g=[1 0 1]
g1=[0 0 1 0 1]
f+g1
f-g1
conv(f,g)
[q,r]=deconv(f,g)
polyder(f)
066各种插值运算：
X=0:0.1:pi/2;
Y=sin(X);
interp1(X,Y,pi/4)
interp1(X,Y,pi/4,'nearest')
interp1(X,Y,pi/4,'spline')
interp1(X,Y,pi/4,'cubic')
067曲线的拟合：
X=0:0.1:2*pi;
Y=cos(X);
[p,s]=polyfit(X,Y,4)
plot(X,Y,'K*',X,polyval(p,X),'r-')
068求函数的最值与0点
x=2:0.1:2;
[x,y]=fminbnd('x.^3-2*x+1',-1,1) [x,y]=fzero('x.^3-2*x+1',1)
069求多项式的表达式、值、及图像
y=[1 3 5 7 19]
t=poly(y)
x=-4:0.5:8
yx=polyval(t,x)
plot(x,yx)
070数据的拟合与绘图
x=0:0.1:2*pi;
y=sin(x);
p=polyfit(x,y,5);
y1=polyval(p,x)
plot(x,y,'b',x,y1,'r')
071求代数式的极限：
syms x
f=sym('log(1+2*x)/sin(3*x)');
b=limit(f,x,0)
072求导数与微分
syms x
f=sym('x/(cos(x))^2');
y1=diff(f)
y2=int(f,0,1)
078划分网格函数
[x,y]=meshgrid(-2:0.01:2,-3:0.01:5); t=x.*exp(-x.^2-y.^2);
[px,py]=gradient(t,0.05,0.1);
td=sqrt(px.^2+py.^2);
subplot(221)
imagesc(t)
subplot(222)
imagesc(td)
colormap('gray')
079求多次多项方程组的解：
syms x1 x2 a ;
eq1=sym('x1^2+x2=a')
eq2=sym('x1-a*x2=0')
[x1 x2]=solve(eq1,eq2,x1,x2)
v=solve(eq1,eq2)
v.x1
v.x2
an1=x1(1),an2=x1(2)
an3=x2(1),an4=x2(2)
080求解微分方程：
[y]=dsolve('Dy=-y^2+6*y','y(0)=1','x')
s=dsolve('Dy=-y^2+6*y','y(0)=1','x')
[u]=dsolve('Du=-u^2+6*u','u(0)=1')
w=dsolve('Du=-u^2+6*u','z')
[u,w]=dsolve('Du=-w^2+6*w,Dw=sin(z)','u(0)=1,w(0)=0','z') v=dsolve('Du=-w^2+6*w,Dw=sin(z)','u(0)=1,w(0)=0','z')
081各种显现隐含函数绘图：
f=sym('x^2+1')
subplot(221)
ezplot(f,[-2,2])
subplot(222)
ezplot('y^2-x^6-1',[-2,2],[0,10])
x=sym('cos(t)')
y=sym('sin(t)')
subplot(223)
ezplot(x,y)
z=sym('t^2')
subplot(224)
ezplot3(x,y,z,[0,8*pi])
082极坐标图：
r=sym('4*sin(3*x)')
ezpolar(r,[0,6*pi])
083多函数在一个坐标系内：
x=0:0.1:8;
y1=sin(x);
subplot(221)
plot(x,y1)
subplot(222)
plot(x,y1,x,y2)
w=[2 3;3 1;4 6]
subplot(223)
plot(w)
q=[4 6:3 5:1 2]
subplot(224)
plot(w,q)
084调整刻度图像：
x=0:0.1:10;
y1=sin(x);
y2=exp(x);
y3=exp(x).*sin(x);
subplot(221)
plot(x,y2)
subplot(222)
loglog(x,y2)
subplot(223)
plotyy(x,y1,x,y2)
085等高线等图形，三维图：t=0:pi/50:10*pi;
subplot(2,3,1)
plot3(t.*sin(t),t.*cos(t),t.^2) grid on
[x,y]=meshgrid([-2:0.1:2])
z=x.*exp(-x.^2-y.^2)
subplot(2,3,2)
plot3(x,y,z)
box off
subplot(2,3,3)
meshz(x,y,z)
subplot(2,3,4)
surf(x,y,z)
contour(x,y,z)
subplot(2,3,6)
surf(x,y,z)
subplot(2,3,5)
contour(x,y,z)
box off
subplot(2,3,6)
contour3(x,y,z)
axis off
086统计图
Y=[5 2 1;8 7 3;9 8 6;5 5 5;4 3 2]
subplot(221)
bar(Y)
box off
subplot(222)
bar3(Y)
subplot(223)
barh(Y)
subplot(224)
bar3h(Y)
087面积图
Y=[5 1 2;8 3 7;9 6 8;5 5 5;4 2 3];
subplot(221)
area(Y)
grid on
set(gca,'Layer','top','XTick',1:5)
sales=[51.6 82.4 90.8 59.1 47.0];
x=90:94;
profits=[19.3 34.2 61.4 50.5 29.4];
subplot(222)
area(x,sales,'facecolor',[0.5 0.9 0.6], 'edgecolor','b','linewidth',2) hold on
area(x,profits,'facecolor',[0.9 0.85 0.7], 'edgecolor','y','linewidth',2) hold off
set(gca,'Xtick',[90:94])
set(gca,'layer','top')
gtext('\leftarrow 销售量') gtext('利润')
gtext('费用')
xlabel('年','fontsize',14)
088函数的插值：
x=0:2*pi;
y=sin(x);
xi=0:0.1:8;
yi1=interp1(x,y,xi,'linear')
yi2=interp1(x,y,xi,'nearest') yi3=interp1(x,y,xi,'spline')
yi4=interp1(x,y,xi,'cublic')
p=polyfit(x,y,3)
yy=polyval(p,xi)
subplot(3,2,1)
plot(x,y,'o')
subplot(3,2,2)
plot(x,y,'o',xi,yy)
subplot(3,2,3)
plot(x,y,'o',xi,yi1)
subplot(3,2,4)
plot(x,y,'o',xi,yi2)
subplot(3,2,5)
plot(x,y,'o',xi,yi3)
subplot(3,2,6)
plot(x,y,'o',xi,yi4)
089二维插值计算：
[x,y]=meshgrid(-3:0.5:3);
z=peaks(x,y);
[xi,yi]=meshgrid(-3:0.1:3); zi=interp2(x,y,z,xi,yi,'spline') plot3(x,y,z)
hold on
mesh(xi,yi,zi+15)
hold off
axis tight
090函数表达式;
function f=exlin(x)
if x<0
f=-1;
elseif x<1
f=x;
elseif x<2
f=2-x;
else
f=0;
end
091：硬循环语句:
n=5;
for i=1:n
for j=1:n
if i==j
a(i,j)=2;
else
a(i,j)=0;
end
end
end
while 循环语句：
n=1;
while prod(1:n)<99^99;
n=n+1
end
n
:092 switch开关语句
a=input('a=?')
switch a
case 1
disp('It is raning') case 0
disp('It do not know')
case -1
disp('It is not ranging')
otherwise
disp('It is raning ?')
end
093画曲面函数：
x1=linspace(-3,3,30)
y1=linspace(-3,13,34)
[x,y]=meshgrid(x1,y1);
z=x.^4+3*x.^2-2*x+6-2*y.*x.^2+y.^2-2*y; surf(x,y,z)。