一第一类贝塞尔函数第一类贝塞尔函数的代码如下：clear allx=(0:0.01:25);J0=besselj(0,x);J1=besselj(1,x);J2=besselj(2,x);J3=besselj(3,x);plot(x,J0,:,x,J1,-.,x,J2,-,x,J3,-);axis(0,25,-1,1);grid onxlabel(X);ylabel(J(X);title(第一类贝塞尔函数曲线图);text(1,0.8,J0(X);text(2,0.6,J1(X);text(4,0.4,J2(X);text(12,0.2,J3(x);二第二类贝塞尔函数第二类贝塞尔函数的代码如下：clear all；clc；x=(0:0.01:25);Y0=bessely(0,x);Y1=bessely(1,x);Y2=bessely(2,x);Y3=bessely(3,x);plot(x,Y0,:,x,Y1,-.,x,Y2,-,x,Y3,-);axis(0,25,-1,1);text(2,0.6,Y0(X);text(4,0.4,Y1(X);text(11,0.24,Y2(X);text(13,0.24,Y3(X);grid onxlabel(X);ylabel(Y(X);title(第二类贝塞尔函数曲线图);三第一类修正贝塞尔函数第一类修正贝塞尔函数的代码如下：clear all；clc；x=(0:0.01:25);I0=besseli(0,x);I1=besseli(1,x);I2=besseli(2,x);I3=besseli(3,x);plot(x,I0,:,x,I1,-.,x,I2,-,x,I3,-);axis(0,5,0,10);text(0.5,1.3,I0(X);text(2.5,2,I1(X);text(3.5,3.1,I2(X);text(4.4,5,I3(X);grid onxlabel(X);ylabel(I(X);title(第一类修正贝塞尔函数曲线图);四第二类修正贝塞尔函数第二类修正贝塞尔函数的代码如下：clear all；clc；x=(0:0.01:20);K0=besselk(0,x);K1=besselk(1,x);K2=besselk(2,x);K3=besselk(3,x);plot(x,K0,:,x,K1,-.,x,K2,-,x,K3,-);axis(0,5,0,10);text(0.5,0.5,K0(X);text(0.3,3.5,K1(X);text(1,2,K2(X);text(1.8,1,K3(X);grid onxlabel(X);ylabel(K(X);title(第二类修正贝塞尔函数曲线图);5 阶跃函数阶跃函数的代码如下：clear allclc;format longha=0:0.01:12;a=0:0.001:2;b=0:0.001:5;c=0:0.001:8;y=ha.*besselj(1,ha)./besselj(0,ha);y1=sqrt(4-a.2).*besselk(1,sqrt(4-a.2)./besselk(0,sqrt(4-a.2);y2=sqrt(25-b.2).*besselk(1,sqrt(25-b.2)./besselk(0,sqrt(25-b.2);y3=sqrt(64-c.2).*besselk(1,sqrt(64-c.2)./besselk(0,sqrt(64-c.2);h=plot(ha,y,k-,a,y1,r-,b,y2,b-,c,y3,g-,linewidth,1.2);grid onaxis(0,12,-15,15);title(l=0时图解法确定LP模的ha);text(0.5,3.5,V=2);text(3,5,V=5);text(4,8,V=8);xlabel(ha);ylabel( Y);set(h,LineSmoothing,on);