bessl2r.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=[20,2,1.1];
w=sqrt(u);
b=1-a;
for i=1:3
    A=Q/(a*besseli(0,w)+a*besselk(0,w)*(besseli(1,w*R(i))/besselk(1,w*R(i)))+b*w*besseli(1,w)-b*w*besselk(1,w)*(besseli(1,w*R(i))/besselk(1,w*R(i))));
    B=Q/(a*besseli(0,w)*(besselk(1,w*R(i))/besseli(1,w*R(i)))+a*besselk(0,w)+b*w*besseli(1,w)*(besselk(1,w*R(i))/besseli(1,w*R(i)))-b*w*besselk(1,w));
    x=-1:0.01:1;
    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');
        end;
        hold on;
    end;
    hold off;
    axis([-1 1 -1 3 ]);
    legend('R= 20','R= 3','R= 1.1',0);
    title('第二种边界条件下不同R值的图象','FontSize',12,'FontName','隶书');