solute.m

fit programme for a serials of data

function X=solute(A,b)
% input A is an N*N nonsingular matrix
%       b is an N*1 matrix
% output X is the solution of AX=b
[L,U]=ltriangsec(A);
[n,n]=size(A);
Y=zeros(n,1);
X=zeros(n,1);
for i=1:n
    Y(i)=b(i);
    for j=1:i-1
       Y(i)=Y(i)-L(i,j)*Y(j); 
    end
end
for i=n:-1:1
    X(i)=Y(i);
    for j=i+1:n
       X(i)=X(i)-U(i,j)*X(j); 
    end
    X(i)=X(i)/U(i,i);
end