找列主元高斯消去法来求解线性代数方程组解的matlab程序

Answer 1

高斯列主元消去法

function X=Gauss_pivot(A,B)

% 用Gauss列主主元消去法解线性方程组AX=B

%X是未知向量

n=length(B);

X=zeros(n,1);

c=zeros(1,n);

d1=0

for i=1:n-1

max=abs(A(i,i));

m=i;

for j=i+1:n

if max<abs(A(j,i))

max=abs(A(j,i));

m=j;

end

end

if(m~=i)

for k=i:n

c(k)=A(i,k);

A(i,k)=A(m,k);

A(m,k)=c(k);

end

d1=B(i);

B(i)=B(m);

B(m)=d1;

end

for k=i+1:n

for j=i+1:n

A(k,j)=A(k,j)-A(i,j)*A(k,i)/A(i,i);

end

B(k)=B(k)-B(i)*A(k,i)/A(i,i);

A(k,i)=0;

end

end

%回代求解

X(n)=B(n)/A(n,n);

for i=n-1:-1:1

sum=0;

for j=i+1:n

sum=sum+A(i,j)*X(j);

end

X(i)=(B(i)-sum)/A(i,i);

End

Answer 2

function X=Gauss_pivot(A,B)
n=length(B);
X=zeros(n,1);
c=zeros(1,n);
d1=0
for i=1:n-1
max=abs(A(i,i));
m=i;
for j=i+1:n
if max<abs(A(j,i))
max=abs(A(j,i));
m=j;
end
end
if(m~=i)
for k=i:n
c(k)=A(i,k);
A(i,k)=A(m,k);
A(m,k)=c(k);
end
d1=B(i);
B(i)=B(m);
B(m)=d1;
end
for k=i+1:n
for j=i+1:n
A(k,j)=A(k,j)-A(i,j)*A(k,i)/A(i,i);
end
B(k)=B(k)-B(i)*A(k,i)/A(i,i);
A(k,i)=0;
end
end
X(n)=B(n)/A(n,n);
for i=n-1:-1:1
sum=0;
for j=i+1:n
sum=sum+A(i,j)*X(j);
end
X(i)=(B(i)-sum)/A(i,i);
end

Answer 3