www.pudn.com > MATLABpro.rar > sanci2.m

%x=-1:0.01:1; 
%y1=5000./(1+25.*x.^2).^3.*x.^2-50./(1+25.*x.^2).^2; 
function sm=sanci2(x,y,x1) 
y1=0; 
y11=0; 
n=length(x); 
h(1)=x(2)-x(1); 
for i=2:n-1 
    h(i)=x(i+1)-x(i); 
    lm(i)=h(i)/(h(i-1)+h(i)); 
    mu(i)=1-lm(i); 
    c1(i)=3*(lm(i)*(y(i)-y(i-1))/h(i-1)+mu(i)*(y(i+1)-y(i))/h(i)); 
end 
c1(1)=3*(y(2)-y(1))/h(1)-h(1)*y1/2; 
c1(n)=3*(y(n)-y(n-1))/h(n-1)-h(n-1)*y11/2; 
c(1:n)=c1(1:n); 
a=2*ones(1,n); 
b=[lm(2:n-1) 1]; 
d=[1 mu(2:n-1)]; 
X=trisys(d,a,b,c); 
m(1:n)=X; 
%x1=-0.9:0.1:0.9; 
L=length(x1); 
for k=1:L 
    for i=1:n-1 
        if (x1(k)>=x(i)&x1(k)<=x(i+1)) 
            t=(x1(k)-x(i))/h(i); 
            u1=(1+2*t)*(t-1)^2; 
            u2=t*(t-1)^2; 
            u3=t^2*(3-2*t); 
            u4=t^2*(t-1); 
            sm(k)=y(i)*u1+h(i)*m(i)*u2+y(i+1)*u3+h(i)*m(i+1)*u4; 
       end 
   end 
end 
%plot(x,fg(x),x1,sm,'r'); 
%hold on;