实验十五及英语作文
六年级 记叙文 2257字 209人浏览 小杰爱菜菜

英语期末考试作文题出来了

how does Internet change your life?

Since internet is available everywhere, all my friends mail me. And we keep circulating our documents and regular greets on this....We now chat, correspond, blog, shop, browse, listen to music, learn, work, update ourselves, govern countries, run corporations, and much much more, via the Internet. It has given me the opportunity to learn beyond my wildest dreams. It has provided me with a wealth of knowledge at my fingertips. It's has allowed me the priviledge to know tons of people from all walks of life from all over the world. It has made me realize what my potentials are and how I can do whatever I want to do in life. I don't know how I can live without it!

%实验十五 综合实验

%第一题

%定义函数文件

function zp=fs(z,n)

zp=0;

z=0;

for k=1:n;

z=1+imag(z)-1.4*real(z)^2+i*real(z)*0.3;

zp=[zp,z];

end

%在主窗口调用该函数:

n=30000;

z=0;

zp=fs(z,n);

plot(zp,'p','markersize',2,'color','r')

%第二题

quad('1/sqrt(2*pi)*exp(-x.*x/2)',0,1)

syms x

int(1/sqrt(2*pi)*exp(-x.*x/2),0,1)

%第三题

%定义函数文件

function dx=apollo(t,x)

mu=1/82.45;

mustar=1-mu;

r1=sqrt((x(1)+mu)^2+x(3)^2);

r2=sqrt((x(1)-mustar)^2+x(3)^2);

dx=[x(2);2*x(4)+x(1)-mustar*(x(1)+mu)/r1^3-mu*(x(1)-mustar)/r2^3;

x(4);-2*x(2)+x(3)-mustar*x(3)/r1^3-mu*x(3)/r2^3];

%在主窗口调用该函数:

x0=[1.2;0;0;-1.04935751];

options=odeset('reltol',1e-8);

%该命令的另一种写法是options=odeset;options.reltol=1e-8;

[t,y]=ode45(@apollo,[0,20],x0,options);

plot(y(:,1),y(:,3))%绘制x 和y 图像,也就是卫星的轨迹

title('Appollo卫星运动轨迹')

xlabel('X')

ylabel('Y')

%第四题

%这是一个力矩平衡问题,可列方程:500×1.5×cos α=400×2.0×cos(π/3-α)

%解得α=26.8021°。

%程序一:迭代法解方程

x1=input('x1=?');

x=pi/3.0-acos(15.0*cos(x1)/16);

while abs(x-x1)>=10e-8

x1=x;

x=pi/3.0-acos(15.0*cos(x1)/16);

if x>pi/3.0

disp('error');

end

end

y=x1*180/pi

%程序二:利用绘图功能

%分别绘制两个小孩所产生力矩随α变化的曲线,两曲线的交点即是跷跷板平衡时的α alpha=linspace(0,pi/2,80000);

m1=500*1.5*cos(alpha); %第一个小孩产生的力矩

m2=400*2*cos(pi/3-alpha); %第二个小孩产生的力矩

k=find(abs(m1-m2)<1e-2); %找平衡点

alpha0=alpha(k);

m0=500*1.5*cos(alpha0);

plot(alpha,m1,alpha,m2,alpha0,m0,'kp'); alpha=alpha0*180/pi %

化为角度

%第五题

clear; close;

fplot('18-t^(2/3)',[0,20]);grid on;hold on;

fplot('5+t+2*t^(2/3)',[0,20],'r');hold off;

%发现t 约为4

[t,f,h]=fsolve('18-x^(2/3)-5-x-2*x^(2/3)',4)

%求得t=4.6465

t=linspace(0,t,100); y=18-t.^(2/3)-5-t-2*t.^(2/3);

trapz(t,y)-20

%最大利润6.3232(百万元)