bessl3r.m

主要阐述的是使用差分法解一类Bessel方程在不同边界条件下的离散解

clear;
Q=1,a=2,u=1,R=[40,20,2,1.5];
w=sqrt(u);
b=1-a;
for i=1:4
    A=Q/(a*besseli(0,w)-a*besselk(0,w)*(besseli(0,w*R(i))/besselk(0,w*R(i)))+b*w*besseli(1,w)+b*w*besselk(1,w)*(besseli(0,w*R(i))/besselk(0,w*R(i))));
    B=Q/(a*besselk(0,w)-a*besseli(0,w)*(besselk(0,w*R(i))/besseli(0,w*R(i)))-b*w*besseli(1,w)*(besselk(0,w*R(i))/besseli(0,w*R(i)))-b*w*besselk(1,w));
    x=-1.5:0.05:1.5;
    y=A*besseli(0,w*x)+B*besselk(0,w*x);
   switch i
        case 1,
            plot(x,y,'k');
        case 2,
            plot(x,y,' . k');
        case 3,
            plot(x,y,' -- k');
        case 4,
            plot(x,y,' * k');
        end;
        hold on;
    end;
    hold off;
    axis([-1.5 1.5 0 1 ]);
    legend('R= 40','R= 20','R= 3','R= 1.1',0);
    title('第三种边界条件下不同R值的图象','FontSize',12,'FontName','隶书');