syms x
b=limit((sqrt(1+x^2)-1)/(1-cos(x)))

syms x a
b=limit((1+a/x)^2,x,inf)

syms x
dy=diff(log((x+2)/(1-x)),3)
dy=simplify(dy)   %对符号函数进行化简
pretty(dy)        %分数线居中显示，这部一般不需要

a=[0,0.5,2,4];
da=diff(a)

syms x
y=x^3+6*x^2+8*x-1;
dy=diff(y);
dy_zero=solve(dy)  %表达式类型
dy_zero_num=double(dy_zero) %变成数值类型
ezplot(y)

syms x
y=x^3+6*x^2+8*x-1;
dy=diff(y);
dy_zero=solve(dy)  %表达式类型
dy_zero_num=double(dy_zero) %变成数值类型
ezplot(y)  %符号曲线画图

syms x
I=int(1/(1+sqrt(1-x^2)))
pretty(I)

syms x
I=int(cos(x)*cos(2*x),-pi/2,pi/2)

I=quadl(@(t)(t-3*t.^2+2*t.^3).^(-1/3),eps,0.5)

syms t  %不加也可以
I=quadl('(t-3*t.^2+2*t.^3).^(-1/3)',eps,0.5) %后面两项分别为积分上下限，eps认为是0

I=dblquad(@(x,y)sqrt(1-x.^2-y.^2).*(x.^2+y.^2<=x),0,1,-0.5,0.5)

fun3=@(x,y,z)z.^2*log(x.^2+y.^2+z.^2+1)./(x.^2+y.^2+z.^2+1).*(z>=0&...
    z<=sqrt(1-x.^2-y.^2)); %...是续航符
I=triplequad(fun3,-1,1,-1,1,0,1)

syms n
f1=(2*n-1)/2^n;
s1=symsum(f1,n,1,inf)

syms n
f2=1/n^2
s2=symsum(f2,n,1,inf)

title('my title')
xlabel('x-axis label')
ylabel('y-scid label')
text(x,y,'text for annotation')
gtext('text for annotation')
grid  %网格的打开与关闭
subplot(r,c,p)
plot(t,[x1,x2,x3])
plot(t1,x1,t2,x2,t3,x3)
plot(x,y,'r-*')

function y=Afun1(x);
if x<1
    y=x+1;
else 
    y=1+1/x;
end

fplot('Afun1',[-3,3])

Afun2=@(x)(x+1)*(x<1)+(1+1/x)*(x>=1);
fplot(Afun2,[-3,3]);

ezplot('tan(x)')
ezplot('x^2+y^2/4=1')

t=0:pi/50:10*pi
plot3(sin(t),cos(t),t);
xlabel('sin(t)'),ylabel('cos(t)'),zlabel('t')

clc,clear
x=-3:0.1:3;y=-5:0.1:5;
[x,y]=meshgrid(x,y);   %生成网格数据,自变量
z=(sin(x.*y)+eps)./(x.*y+eps);   %为避免0/0，分子分母都加eps
mesh(x,y,z);

[x,y]=meshgrid([-3:0.2:3]);
z=(sin(x.*y)+eps)./(x.*y+eps);
surf(x,y,z);

x=0:10:600;
[X,Y,Z]=cylinder(30*exp(-x/400).*sin((x+25*pi)/100)+130);
surf(X,Y,Z)

alpha=[0:0.1:2*pi]';
beta=0:0.1:2*pi;
x=4*cos(alpha)*ones(size(beta));
y=(5+4*sin(alpha))*cos(beta);
z=(5+4*sin(alpha))*sin(beta);
surf(x,y,z)

x=@(alpha,beta)4*cos(alpha);
y=@(alpha,beta)(5+4*sin(alpha)).*cos(beta);
z=@(alpha,beta)(5+4*sin(alpha)).*sin(beta);
ezsurf(x,y,z)

x=@(s,t)3*sec(s).*cos(t);
y=@(s,t)3*sec(s).*sin(t);
z=@(s,t)2*tan(s);
ezmesh(x,y,z);

x=@(s,t)3*sec(s);
y=@(s,t)3*tan(s).*cos(t);
z=@(s,t)2*tan(s).*cos(t);
ezmesh(x,y,z);

ezsurf(@(y,z)y.^2,50);

x=@(s,t)3*tan(s).*cos(t);
y=@(s,t)2*tan(s).*sin(t);
z=@(s,t)tan(s);
ezsurf(x,y,z);

ellipsoid(0,0,0,3,2,sqrt(6));

ezsurf(@(x,y)x.*y);

x=@(s,t)3*cos(s);
y=@(s,t)2*sin(s);
z=@(s,t)t;
ezmesh(x,y,z)

[x,y,z,v]=flow;
isosurface(x,y,z,v);

x=1:20;y=1:10;z=-10:10;
[x,y,z]=meshgrid(x,y,z);
v=x.^2.*y.*(z+1);
isosurface(x,y,z,v);