(CODE Matlab) Môn Phương Pháp Tính và Matlab ĐH BKHN

% Ho va ten: Nguyen Van Luong
% MSSV: 20146959
% De so 2

%Bai3. a) Giai phuong trinh bai 1-c su dung phuong phap Newton
disp('Nhap vao cac he so cua phuong trinh:');
a1=input('He so thu 1:');
a2=input('He so thu 2:');
a3=input('He so thu 3:');
a4=input('He so thu 4:');
% Khoi tao ham so
fx=[a1 a2 a3 a4];
% Dao ham cua f(x)
ffx=polyder(fx);
% Chon x0 thuoc khoang phan ly nghiem
x0=-6;
% Xac dinh nghiem xap xi thu n
n=1;
while n<6
x=x0-polyval(fx,x0)/polyval(ffx,x0);
x0=x;
n=n+1;
end
disp('Nghiem gan dung cua phuong trinh: x=');
disp(x);


%Bai3. a) Giai he bai 2-b su dung Gauss – Jordan


disp('Nhap vao cac he so cua he phuong trinh dang ma tran mo rong (A|b):');

a11=input('a11 ='); a12=input('a12 ='); a13=input('a13 ='); a14=input('a14
=');b1=input('b1 =');
a21=input('a21 ='); a22=input('a22 ='); a23=input('a23 ='); a24=input('a24
=');b2=input('b2 =');
a31=input('a31 ='); a32=input('a32 ='); a33=input('a33 ='); a34=input('a34
=');b3=input('b3 =');
a41=input('a41 ='); a42=input('a42 ='); a43=input('a43 ='); a44=input('a44
=');b4=input('b4 =');


% Khoi tao ma tran
A=[a11 a12 a13 a14 b1;a21 a22 a23 a24 b2;a31 a32 a33 a34 b3;a41 a42 a43 a44
b4];
disp('He phuong trinh viet duoi dang ma tran A|b'); disp(A);
% Tinh kich thuoc A
s=size(A);
% n Xác dinh ma tran vuong gom cac he so cua ve trai he phuong trinh
n=min(s);
for i=1:n


% Dua hàng co he so lon nhat len dau
[t,r]=max(abs(A(i:end,i)));
t=A(r+i-1,:);
A(r+i-1,:)=A(i,:);
A(i,:)=t;
% Chia cac he so cua hàng i cho phan tu [i,i]
A(i,[1:i-1 i+1:end])=A(i,[1:i-1 i+1:end])/A(i,i);
% Dua phan tu [i,i] ve gia tri 1
A(i,i)=1;

% Vector hang s gom cac phan tu cua hàng i tru di phan tu [i,i]
s=A(i,i+1:end);


% Rut gon các hang trong ma tran moi không chua hàng i,cot i theo he so
% cua hàng i
for j=[1:i-1 i+1:n]
A(j,i+1:end)=A(j,i+1:end)-A(j,i).*s;
end
% Dua cac phan tu cot i, ngoài phan tu [i,i] ve 0
A([1:i-1 i+1:end],i)=0;

end


disp('He phuong trinh sau khi bien doi Gauss-Jordan'); disp(A);
disp('Vay nghiem cua he la:');
disp('x1='); disp(A(1,5));
disp('x2='); disp(A(2,5));
disp('x3='); disp(A(3,5));
disp('x4='); disp(A(4,5));


% Ho va ten: Nguyen Van Luong
% MSSV: 20146959
% De so 2
% Bai nay em dung function nên phai luu sang 1 file khac thay a !

%Bai 3. b) Ham nhap vector co chieu dai 6
function result = bai3b(a,b,c,d,e,f)

% INPUT 6 phan tu cua vector
% Tao vector v voi 6 phan tu dau vao
v=[a b c d e f];

% i. Tim gia tri lon nhat cua cac phan tu vector
maxv = max(v);
disp('Phan tu lon nhat cua vector v:'); disp(maxv);


% ii. Tinh tong cac phan tu vector v
tong=0;n=1;
while(n<7)
tong=tong+v(n);
n=n+1;
end
disp('Tong cac phan tu cua vector:'); disp(tong);

% iii. In ra cac phan tu la boi cua 3
disp('Cac phan tu la boi cua 3:')
k=1;
while(k<7)
if mod(v(k),3) == 0; disp(v(k)); end
k=k+1;
end


% iv. coi v la da thuc bac 5, nhap da thuc t bac 9 va tinh tong 2 da thuc
disp('Nhap vao cac he so cua da thuc bac 9');
x1=input('Nhap vao he so thu 1:');
x2=input('Nhap vao he so thu 2:');

x3=input('Nhap vao he so thu 3:');
x4=input('Nhap vao he so thu 4:');
x5=input('Nhap vao he so thu 5:');
x6=input('Nhap vao he so thu 6:');
x7=input('Nhap vao he so thu 7:');
x8=input('Nhap vao he so thu 8:');
x9=input('Nhap vao he so thu 9:');
x10=input('Nhap vao he so thu 10:');
% Khoi tao da thuc
t=[x1 x2 x3 x4 x5 x6 x7 x8 x9 x10];
g=abs(length(v) - length(t));
vector0 = zeros(1,g);
v=[vector0 v];
vectortong=v+t;
% Tinh tong hai da thuc
disp('Tong cua 2 da thuc:');
disp(vectortong);

end