bvp.m

sareli<matlab科学计算>配套程序

function [x,uh]=bvp(a,b,N,delta,gamma,fun,ua,ub)
%BVP Solve two-point boundary value problem
%   [X,UH]=BVP(A,B,N,DELTA,GAMMA,FUN,UA,UB) solves with the
%   centered finite difference method the boundary-value
%   problem
%       -D(DU/DX)/DX+DELTA*DU/DX+GAMMA*U=FUN  
%   on the interval (A,B) with boundary conditions U(A)=UA
%   and U(B)=UB.
%   FUN can be an inline function.
h = (b-a)/(N+1); 
z = linspace(a,b,N+2); 
e = ones(N,1);
A = spdiags([-e-0.5*h*delta 2*e+gamma*h^2 -e+0.5*h*delta], -1:1, N, N); 
x = z(2:end-1); 
f = h^2*feval(f,x); 
f=f';   f(1) = f(1) + ua;   f(end) = f(end) + ub;
uh = A\f; 
uh=[ua; uh; ub]; 
x = z;