% plot1.m 96/07/14
%
% Program to plot simple graph of integral of surface
% 

    y=(1:.1:3);
    z1=4-.5*(y-2).^2;
    z2=4-.5*(.2)^2-.5*(y-2).^2;
    x1=2*ones(size(y));
    x2=2.2*ones(size(y));
    [X,Y]=meshgrid(1:.1:3);
    Z=4-.5*(X-2).^2-.5*(Y-2).^2;

%   hold off;
    colormap('white');
    plot3(x1,y,z1,'w-');
    hold on
    plot3(x2,y,z2,'w-');
    axis([0 4 0 4 0 4]);
    plot3([1 1],[1 3],[0 0],'w--'); 
    plot3([3 3],[1 3],[0 0],'w--'); 
    plot3([1 3],[1 1],[0 0],'w--'); 
    plot3([1 3],[3 3],[0 0],'w--'); 
    plot3([2 2],[1 1],[0 3.5],'w--');
    plot3([2 2],[3 3],[0 3.5],'w--');
    plot3([2 2],[.8 3],[0 0],'w--');
    plot3([2.2 2.2],[1 1],[0 z2(1)],'w--');
    plot3([2.2 2.2],[3 3],[0 z2(1)],'w--');
    plot3([2 2.2],[1 1],[z1(1) z2(1)],'w--');
    plot3([2 2.2],[3 3],[z1(1) z2(1)],'w--');
    plot3([2.2 2.2],[.8 3],[0 0],'w--');
    text(1.1,.5,0,'a');
    text(3.0,.5,0,'b');
    text(.4,1.2,0,'c');
    text(.4,3.2,0,'d');
    text(1.3,2.5,0,'R')
    text(1.8,0.5,0,'x');
    text(2.2,0.6,0,'x+dx');
    xlabel('x');
    ylabel('y');
    zlabel('z');
    hold off;
