Tổng hợp code các bài tập thực hành matlab

Bai 1 clc x=-2:0.01:2 y=exp(-0.3.*x.^2- 0.5.*x +1).*cos(20.*x) subplot(2,1,1)% lenh subplot nay chia man %hinh do thi theo 2 hang 1 cot vi tri 1 plot(x,y,'m')%lenh nay ve do thi vao phan %hinh minh chia ra vào subplot 1 %hinhcon 2 subplot(2,1,2) % ve dang ham nay thi khai bao truc tiep ham trong dau '' fplot('exp(-0.3.*x.^2- 0.5.*x+1).*cos(20.*x)',[-2 2]) title('do thi ham so ')% lenh nay dien %tieu de cho do thi xlabel('truc x')% ghi tieu de cho truc x xlabel('truc y')% ghi tieu de cho truc y

Cao V¨n ChÝnh_B1K52 Tổng hợp code các bài thực hành Matlab

Bai 1

clc

x=-2:0.01:2

y=exp(-0.3.*x.^2- 0.5.*x +1).*cos(20.*x)

subplot(2,1,1)% lenh subplot nay chia man

%hinh do thi theo 2 hang 1 cot vi tri 1

plot(x,y,'m')%lenh nay ve do thi vao phan

%hinh minh chia ra vào subplot 1

%hinhcon 2

subplot(2,1,2)

% ve dang ham nay thi khai bao truc tiep ham trong dau ''

fplot('exp(-0.3.*x.^2- 0.5.*x+1).*cos(20.*x)',[-2 2])

title('do thi ham so ')% lenh nay dien

%tieu de cho do thi

xlabel('truc x')% ghi tieu de cho truc x

xlabel('truc y')% ghi tieu de cho truc y

Bai 2

%hinh con 1

x=0:0.05:4;y=3.*sin(pi.*x);y1=exp(-0.2.*x)

subplot(2,1,1);plot(x,y,'r',x,y1,'b')

gtext('giao diem 1')% gan chu thich vao

%cac giao diem giua 2 do thi

subplot(2,2,3);bar(x1,y2)% ve do thi dang cot

subplot(2,2,4);stairs(x1,y2)%ve do thi dang bac thang

Bai 3

-% Chu y ham function o day chi chay dc tren Window thui,voi may tinh tren truong thi khong chay duoc dau!!!

Cao V¨n ChÝnh_B1K52

Bai 4

[x,y]=meshgrid(-2:.1:2);

z=2.*x.*y./(x.^2 +y.^2 +1);

subplot(2,2,1);mesh(x,y,z);% do thi mesh

title('mesh')% gan chu thich mesh

subplot(2,2,2);surf(x,y,z)% do thi surf

if (n<0)|(n~=round(n))% n khac gia tri da lam tron cua n

fprintf('So n nhap vao khong phai la so nguyen duong')

Cao V¨n ChÝnh_B1K52t5=bai6(5,x);plot(x,t5,'g');hold off;

legend('t0','t2','t3','t4','t5')% gan nha~n cua do thi

% Cau c

figure(2) % Cau c

x=linspace(-1,1);

plot(x,bai6(4,x));ylim([-1.5 1.5])%gioi han do thi

[x0,y0]=ginput;% lay toa do = cach click chuot

f=inline('bai6(4,x)','x');% de y vao ham nay khi tim khong diem

for k=1:length(x0);%do rong cua khong diem

[xn(k) fxn(k)]=fzero(f,x0(k));%ham tim khong diem thuc fzero

%tol la nhap so lieu dang sai so

%thay vi lap dao ham cua fx ta tinh luon dfx

fx=inline(fx);dfx=inline(dfx);%inline la

%1 ham moi ma minh tu dat no dang nhu 1

%function hoac @ ham

k(i)=fx(x0(i))./dfx(x0(i));%chu y chuyen ve

while abs(k(i))<= tol%dieu kien cua tri tuyet doi

%x(1)=x;x(2)=y,ham f lay chuan hoa

[x0 y0]=ginput;;%ginput la ham truy nhap bang chuot lay ket qua tu do thi

for k=1:length(x0)%ham fsolve la ham lay chinh xac nghiem

[xn,yn]=fsolve(f,[x0(k) y0(k)]);

3

Cao V¨n ChÝnh_B1K52

end

fprintf(' Cac cap nghiem cua phuong trinh 1 la:\n');

%fprintf la ham hien thi ra man hinh comand window

contour(x,y,real(f),[0 0],'r');hold on% ve theo phan thuc

contour(x,y,imag(f),[0 0],'b');hold off% ve theo phan ao

disp('Toa do dinh ngoai')

k=1:2:9;% cho k chay tu 1 toi 9 voi buoc nhay la 2

xt=x(k)% toa do theo truc x

yt=y(k)%toa do theo truc y

disp('Toa do dinh trong')

subplot(2,2,1);plot(w,real(G));legend('Dothi Re(G)');%ve theo w va phan thuc

subplot(2,2,2);plot(w,imag(G));legend('Dothi Im(G)');%ve theo w va phan ao

subplot(2,2,3);plot(w,abs(G));legend('Do thi |G|');%ve theo w va tri tuyet doi

4

Cao V¨n ChÝnh_B1K52subplot(2,2,4);plot(w,angle(G));legend('Do thi Arg(G)');%ve theo w va goc pha

% Cau c% tim cuc tri

%Tim cuc tieu

(-1)*fcd %chu y nhan -1 voi fcd

Bai 13 (Chua hiu)

%cau a

clc

5

Cao V¨n ChÝnh_B1K52A01=[19 -9 -6;25 -11 -9;17 -9 -4];

Cao V¨n ChÝnh_B1K52 disp(vn(i))

Cao V¨n ChÝnh_B1K52plot(x,bai16b(bai16a(0),x),'r');hold on

legend('T0','T2','T3','T4','T5')% gan nha~n cua do thi

Bai 17 (chua chay dc)

%Doc lai bai tim tiem can cua do thi ham so

close all; clear; clc;

xv=solve(f2);% tim tiem can dung

fprintf(['Tiem can dung cua do thi ham so:x=',char(xv(1)),' Va ','x=',char(xv(2)),'\n']); yv=limit(f,x,-inf);%tim tiem can ngang

8

Cao V¨n ChÝnh_B1K52fprintf(['Tiem can ngang cua do thi ham so:y=',char(yv),'\n']);

a=limit(f./x,x,inf);%tim tiem can xien

b21=b2(:)%Dua vecto hang thanh cot

% Lam vi du voi a1%

det(a1)%Tim dinh thuc ma tran

inv(a1)%Tim nghich dao ma tran

diag(a1)%Tim duong cheo ma tran

a=poly(a1)%Tim he so da thuc dac trung

p=poly2sym(a)%Tim da thuc dac trung

N=null(a1)%Ma tran chua n vector cuakhong gian 0

v=eig(a1)%Tim tri rieng cua ma tran

[v,d]=eig(a1)%v:ma tran lam cheo; d: dang cheo a1

n=size(N,2)%So chieu cua khong gian khong

rank(a1)%Tim hang ma tran

%tinh chuan cua cac vector b1,b2 va cuacac ma tran A1,A2,A3

fprintf('Chuan cua cac vector b1 & b2 va cua cac ma tran A1,A2,A3la:\n')

fprintf('Dinh thuc cua ma tranA1,A2,A3:\n')

% Tinh dinh thuc cua ma tran dung 'det'

detA1=det(A1)

detA2=det(A2)

detA3=det(A3)

if det(A1)==0

fprintf('Dinh thuc ma tran A= 0\n');

fprintf('Do do khong co ma tran nghic dao\n')

else

fprintf('Dinh thuc ma tran A=');disp(det(A1))

fprintf('Ma tran nghich dao cua A\n');disp(inv(A1));

end

if det(A2)==0

fprintf('Dinh thuc ma tran A= 0\n');

fprintf('Do do khong co ma tran nghic dao\n')

else

fprintf('Dinh thuc ma tran A=');disp(det(A2))

fprintf('Ma tran nghich dao cua A\n');disp(inv(A2));

end

if det(A3)==0

fprintf('Dinh thuc ma tran A= 0\n');

9

Cao V¨n ChÝnh_B1K52fprintf('Do do khong co ma tran nghic dao\n')

else

fprintf('Dinh thuc ma tran A=');disp(det(A3))

fprintf('Ma tran nghich dao cuaA\n');disp(inv(A3));

end

% % Tinh ma tran nghich dao dung 'inv'

% fprintf('Ma tran nghich dao :\n')

%Xac dinh da thuc dac trung cua cac ma tran A1,A2,A3

fprintf('Da thuc dac trung cua cac ma tran A1,A2,A3')

%sang editor khac

clc;clear all;close all

%phan a,b

[x,y]=meshgrid(linspace(-4,4,41))

z=2./((x-1.5).^2+2.*(y-1.8).^2+0.2)-1./(1.5.*(x+1.8).^2+(y+2).^2+0.1)

%cuc dai

[zmax,imax]=max(z) %tim gia tri lon nhat cua mang Z

[zmax,jmax]=max(max(z)) %tim vi tri cot cua gia tri lon nhat

imax=imax(jmax) %tim vi tri hang cua gia tri lon nhat

Cao V¨n ChÝnh_B1K52fx=inline('2./((x(1)-1.5).^2+2.*(x(2)-1.8).^2+0.2)-1./(1.5.*(x(1)+1.8).^2+

contour(x,y,f1,[0 0],'r');hold on;

contour(x,y,f2,[0 0],'m');hold off;

Cao V¨n ChÝnh_B1K52Y=a.*exp(b.*X.^2+c.*X);

Cao V¨n ChÝnh_B1K52subplot(2,2,1)

text(xcd,-fcd,'< cuc dai')

% bang phuong phap noi suy spline

Cao V¨n ChÝnh_B1K52 thang=inline('-ppval(sp,x1)','x1','sp');

plot([k k],[y1(k) y2(k)],'m')%ve duong chia doi

% To mau 2 phan bang nhau bang mau khac nhau

%vung 1: ta lay x chay tu giao dim x=k toi xn(1) cua duong ben tren,

%sau do di tip tu xn(1) toi x=k cua duong ben duoi;vay la het 1 vong di cua ½ dau

x1=linspace(k,xn(1));f1=y1(x1)

x2=linspace(xn(1),k);f2=y2(x2)

%vung 2: ta lay x chay tip tu x=k toi giao dim xn(2) cua duong ben duoi,

%sau do di tip tu xn(2) tro ve x=k cua duong ben tren ; vay la het 1 vong di ½ nua tipx3=linspace(k,xn(2));f3=y1(x3)

%bai toan cauchy

%caua giai hptvp voi dk ban dau [-7.69 -15.61 90.39]);

dy=inline('[10*(u(2)-u(1));126.52*u(1)-u(2)-u(1)*u(3);u(1)*u(2)-8/3*u(3)]','t','u')

[t,u]=ode45(dy,[0 8],[-7.69 -15.61 90.39]);

subplot(2,2,1);plot(t,u(:,1),'r');title('do thi ham x(t)')

subplot(2,2,2);plot(t,u(:,2),'b');title('do thi ham y(t)')

subplot(2,2,3);plot(t,u(:,3),'y');title('do thi ham z(t)')

Cao V¨n ChÝnh_B1K52[yn,dyon]=fzero(f,xo,[],yyo,dyend)

[x,y]=ode45(dy,[0 1],[yn -1]);%Gia tri y(0)va y'(0)

Cao V¨n ChÝnh_B1K52

-

-Tổng hợp code các đề thi Matlab

figure(2); quiver(x,y,dzx,dzy); % ve ham vecto

%tinh gia tri ham Z bang function

Cao V¨n ChÝnh_B1K52[dzx,dzy]=gradient(z);

subplot(1,2,1);plot(x,de3(x,4),'r'); %ve do thi cua tong

subplot(1,2,2);plot(x,de3b(x,1e-8),'b'); %ve dthi cua chuoi

%phan d

%ve mat ron xoay khi quay duong cong quanh truc x

[x,phi]=meshgrid(0 : pi/15 : 2*pi);

Cao V¨n ChÝnh_B1K52x=linspace(0,10);

%ve mat tron xoay khi quay duong cong quanh truc x

[x,phi]=meshgrid(0 : pi/15 : 2*pi);

Cao V¨n ChÝnh_B1K52

0 5 1

- 1 0 1 5 1

- 1 0 1 0

5 1

- 1 0 1

- 1 -5

- 1

- 5 0 5

1-10 1

Cao V¨n ChÝnh_B1K52z1=x.^2-10.*x.*y-4.*y.^4;

%ve do thi phan thuc va phan ao

clear all,close all

%ve phan thuc va phan ao

[x,y]=meshgrid(linspace(-2,2)); %bo di cung dc

% tinh cac duong tiem can

clear all;close all;clc;

Cao V¨n ChÝnh_B1K52fprintf(' yt='); disp(xtcnt);

fprintf('Tiem can ngang ben phai\n');

xtcnp=limit(f,inf);

fprintf(' yp='); disp(xtcnp);

fprintf('Tiem can xien\n');

% Ve tiem can ngang

%tiem can ngang ko xd

% Ve tiem can xien

Cao V¨n ChÝnh_B1K52x1=-1:0.01:2;

Cao V¨n ChÝnh_B1K52

0 0 2 0 4 0 6 0 8 1 1 2 1 4 1 6 1 8 2 1

0 5 1

1 5 2

2 5 3

< k hn d ie m

d ie m th u c n g ie m

hm n o i s u y

De 13

clear all,close all,clc

%noi suy da thuc va noi suy spline

0 5 1

clear all;close all;clc

%dung noi suy da thuc va noi suy spline

%poly2sym(heso,bien) de chuyen doi dang bieu dien cua x sang sym de tinh TP

%tinh dt theo noi suy da thuc (xap xi)

s2=quad(ff,0,44) %cach2 cho ham la ham goc: sym xi;s2=quad(inline(vectorize(y),'x',0,44))

%tinh dt theo noi suy spline

sp=fnint(spl);%tinh tp

s1=ppval(sp,44)-ppval(sp,0)%thay can vao sp de tinh gt tich phan

%tim nghiem bang pp spline ham y(x)=55.7

figure(2)

plot(x1,ppval(spl,x1)-55.7);hold on

26

Cao V¨n ChÝnh_B1K52 plot(x1,0);

%giong bai27, phan cac bai thuc tap

% ve danh gioi va tinh dien tich

clear all,close all;clc

dk=2;%diu kin ban dau dat ra

xm=1.15;%duong chia ranh gioi lay bat ki

fprintf('Duong chia hinh thanh 2 phan co S bang nhau x=');

disp(xm) %gt xm duoc suat ra

s1=quad(f,xn(1),xm) %tinh dt 2 nua, de tim sai so

%vung 1: ta lay x chay tu giao dim x1 toi xm cua duong ben tren,

%sau do quay lai tu xm tro ve x1 cua duong ben duoi;het 1/2 vong

x1=linspace(xn(1),xm,20); y1=30.*sin(x1.^2-0.25);

x2=linspace(xm,xn(1),20); y2=(x2.^4+1)./log(x2+1)-10;

%vung 2: ta lay x chay tu xm toi giao dim x2 cua duong ben tren,

%sau do quay lai tu x2 tro ve xm cua duong ben duoi

Cao V¨n ChÝnh_B1K52

%bit trc [0.7 1.2] ma ko can tin nhu bai 27 va de15,bai nay chia lam 3 phan=

% ve danh gioi va tinh dien tich

clear all,close all;clc

% Ve doan thang 1 x=xm de chia hinh thanh 3phan =

dk=1;xm=0.8;ss=1e-4; %gia su duong chia ban dau la xm=0.8

Cao V¨n ChÝnh_B1K52

0 7 0 7 5 0 8 0 8 5 0 9 0 9 5 1 1 0 5 1 1 1 1 5 1 2 -1 0

-8 -6 -4 -2 0 2 4 6 8 1

x (x4+ 1 )/lo g (x + )-1 0

De 17

%phan a:tinh va ve do thi

%chu y trong khoang gioi han bai ra ta ko thay cuc tieu dau,kaka!!!

%nhung bai nay ta cu viet code de tim cuc tieu, ke no,okok !!!

clear all,close all,clc;

%phan a:tinh va ve do thi

clear all,close all,clc;

%bai toan cauchy

%caua: giai ptvp va ve dthi

Cao V¨n ChÝnh_B1K52 for k=1:length(x11)

%bai toan ve phuong phap ban

%phan a giai ptvp tinh y(x),y'(x)

f=inline('[y(2);y(1)+sin(x)*cos(x)+x^2*sin(x+pi/4)/(x^10+1)]','x','y')

[x y]=ode45(f,[0 5],[0 0])%[0 0] la dk ban dau;[0 5] la gioi han cua x

%cau b: ve do thi y(x) va y'(x) hay y(:,1) va y(:,2)

%[xn(:,k) yn(:,k)]=fsolve(inline('ppval(sp1,x)-ppval(sp2,x)','x'),x0(k))%tai sao khai

%bao the nay thi ko chay dc???????????????

%chu y: hoi cac ban cach giai giong bai 27,de gioi han lai dc hinh ta phai

%lam tnao va neu khai bao inline de chinh xac ngh thi lam tnao?????????

%de20 cach 2, hay hon nhieu cach1 cua Thay Chi

%bai toan ve phuong phap ban

31

Cao V¨n ChÝnh_B1K52

%phan a giai ptvp tinh y(x),y'(x)

f=inline('[y(2);y(1)+sin(x)*cos(x)+x^2*sin(x+pi/4)/(x^10+1)]','x','y')

[x y]=ode45(f,[0 5],[0 0])%[0 0] la dk ban dau;[0 5] la gioi han cua x

%cau b: ve do thi y(x) va y'(x) hay y(:,1) va y(:,2)

%chu y vong lap for o day dung cho ham noi suy

%khac voi vong for dung voi ham so!!!!bai27

legend('y(x)','dy/dx','d2y/dx');%chu thich cho cac duong da ve

%cau b:tim nghiem pt:y(x)=1.5

%chu y vong lap for o day dung cho ham noi suy

%khac voi vong for dung voi ham so!!!!bai27

legend('y(x)','dy/dx','d2y/dx');%chu thich cho cac duong da ve

%cau b:tim nghiem pt:y(x)=1.5

Cao V¨n ChÝnh_B1K52

Cach 1

%cach 1 nay khong chay duoc???????????

clear all;close all;clc;

text(tcd,-ycd,'<cuc dai day ne!!! ')

%chu y co dau tru nhe,bai nay minh thi quyen ko cho dau - vao,huhu !

tcd,-ycd

De 23

clear all;close all;

syms x; %bien syms vi o day ta co buoc tinh dao ham

%Cau a:ve do thi

text(xn,fxn,'< cuc tieu');

%Cau c:Tinh va ve tiem can

a1=limit(y/x,x,inf);a2=limit(y/x,x,-inf);

b1=limit(y-a1*x,x,inf);b2=limit(y-a2*x,x,-inf);

h1=ezplot(a1*x+b1);set(h1,'color','r')

33

Cao V¨n ChÝnh_B1K52 h2=ezplot(a2*x+b2);set(h2,'color','r')

axis([-6 6 -3 14])

%Cau d:tinh do dai cung: bang tich phan sqrt(1+dy^2)

%chu y: tinh dao ham thi bien x phai o dang syms

%tinh dien tich cua vat the xoay quanh ox

%ban kinh vat the chinh la truc oy

disp('dien tich xung quanh');

0 10

20 -15 -10 -5 0 5 10 15

De 24

Chu y: Cau b khong bit lam

clear all;close all;clc

%Cau b:lap function chuyen duong cong bac 2 ve dang chinh tac

%cau b nay ko chay dc,ko hiu gi hit

A=[2,-1/2;-1/2,0];

B=[-5,0];

C=1;

34

Cao V¨n ChÝnh_B1K52 F=de24b(A,B,C)

Cau b khong chay dc dau?????

clear all;close all;clc

%Cau b:lap function chuyen duong cong bac 2 ve dang chinh tac

%cau b nay ko chay dc,ko hiu gi hit

%bai toan ve phuong phap ban

clear all;close all;clc;

subplot(2,1,1);ezplot(y11,[0 5]);grid on %ve ham y

subplot(2,1,2);ezplot(y22,[0 5]);grid on %ve ham y'

Cau a: cach 2

clear all;close all;clc;

%cau a: giai ptvp voi dk ban dau va ve dthi:y,y'

Hay xem lai cach giai PTVP nhe, chua hiu dau day !!!!!!!!!!!!!

Thi tot nhe !

OK !

36