function nma_fem_driver
%script to do a simulation of FEM solution of a second order ODE
%by Nasser Abbasi
%This script calls the m file called nma_fem.m
%
%this solves the ODE
%
%   a u''(t) + b u'(t) + c u(t) = f(t)
%
% with t over the range t0 to len
% and with initial conditions u(0)=u0
% and with u'(len)=beta
%
%To use this to solve an ODE, edit the values below for the variables
% a,b,c,f,len,u0,x0

close all; clear all;

    %   equation 1. u''+u'+u=sin(x)*cos(x). u(0)=1, u'(len)=beta, len=10
    %   maxy=4 miny=-1
    %   a=1, b=1, c=1, x0=0, u0=1,len=10

    a=1;   
    b=1; 
    c=1; 
    x0=0;   % starting domain point
    u0=-10;   
    len=10; 
    beta=1;
    
    ymax=4; ymin=-2;  % for plotting only. To make the plot looks better
    
    %This below solves the equation exactly to compare the FEM solution
    %against.
    
    sol= dsolve('a*D2y+b*Dy+c*y=cos(t)*sin(t)','y(0)=-10','Dy(10)=1');
    sol=subs(sol);

    directory='matlab_ANIMATION/';
    extension='.png';
    
    MAX_NODES = 100;
    for n = 3:MAX_NODES
        ezplot(sol,[0:len,-ymin:ymax]);
        hold on;
        
        r = nma_fem(a,b,c,@f,x0,u0,beta,len,sol,n);  %SOLVES by FEM
        
        title(sprintf('Solving y''''+y''+y(x)=sin(x)*cos(x).  y(0)=1, y''(10)=1. by FEM. \nN=%d\nRMSERROR=%f',n,r));
        drawnow;
        
        image = getframe(gcf);
        p=frame2im(image);
        file_name=[directory num2str(n) extension] ;
        imwrite(p,file_name,'png');
        
        hold off;
        % pause(.5)
    end
end

%%%%%%%%%%%%%%%%%%%%%%%%
%
% edit this below to change the forcing function.
%%%%%%%%%%%%%%%%%%%%%%%%
function v=f(x)
   v=sin(x).*cos(x);
end