a=2; b=5; c=2;
u0=0; u1=1;
n1=10; n2=1000;
h1=1/n1; h2=1/n2;
x1 = [0:h1:1]; x2 = [0:h2:1];
for k=1:(n1+1);
    f1(k)=a*x1(k)+b;
    f2(k)=a*x1(k)+b;
    f3(k)=a*x1(k)+b;
end;
f2(n1+1)=f2(n1+1)-c/(2*h1)+1/h1^2;
f3(1)=f3(1)-u1*(-c/(2*h1)-1/h1^2);
f3(n1+1)=f3(n1+1)-u1*(c/(2*h1)-1/h1^2);
A(1,1)=2/h1^2;
A(1,2)=c/(2*h1)-1/h1^2;
for k=2:n1;
    l=k-1;
    A(k,l)=-c/(2*h1)-1/h1^2;
    A(k,l+1)=2/h1^2;
    A(k,l+2)=c/(2*h1)-1/h1^2;
end;

A(n1+1,n1)=-c/(2*h1)-1/h1^2;
A(n1+1,n1+1)=2/h1^2;
u=f1*inv(A)
u12=f2*inv(A)
u13=f3*inv(A)

%wartosci dokladne
j1=(2*c*c*(u0-u0)-(a*c+2*a+2*b*c))/(2*c*(exp(c)-1));
j2=(2*c*c*(u1-u0)-(a*c+2*a+2*b*c))/(2*c*(exp(c)-1));
j3=(2*c*c*(u1-u1)-(a*c+2*a+2*b*c))/(2*c*(exp(c)-1));

for i=1:n1+1
    ud1(i)= (j1/c)*(exp(c*(i/n1))-1)+(a/(2*c))*(i/n1)*(i/n1)+(a/(c*c)+b/c)*(i/n1)+u0;
end

for i=1:n1+1
    ud2(i)= (j2/c)*(exp(c*(i/n1))-1)+(a/(2*c))*(i/n1)*(i/n1)+(a/(c*c)+b/c)*(i/n1)+u0;
end

for i=1:n1+1
    ud3(i)= (j3/c)*(exp(c*(i/n1))-1)+(a/(2*c))*(i/n1)*(i/n1)+(a/(c*c)+b/c)*(i/n1)+u1;
end
ud1
ud2
ud3
plot(x1,u, '-b',x1,ud1,'-bh', x1, u12,'-r', x1, ud2,'-rh', x1, u13,'-g', x1,ud3,'-gh')