Question

Matlab程序：错误在哪里

建立函数文件fun5.m
function dy=fun5(t,y)
dy=[(-5*sin(t)*(5*cos(t)-y(1))+5*cos(t)*(5*sin(t)-y(2)))*(5*cos(t)-y(1))./((5*cos(t)-y(1))^2+(5*sin(t)-y(2))^2),
(-5*sin(t)*(5*cos(t)-y(1))+5*cos(t)*(5*sin(t)-y(2)))*(5*sin(t)-y(2))./((5*cos(t)-y(1))^2+(5*sin(t)-y(2))^2)]

主程序：
clear,clc
close all
[t,y]=ode45('fun5',[0,100],[10,0]);
X=5*cos(t);
Y=5*sin(t);
figure(1)
plot(X,Y,'r.')
hold on
plot(y(:,1),y(:,2),'*')

Answer 1

标量乘向量还是用点乘吧。

把所有*改成 .*试试行不？

function dy=fun5(t,y)

dy=[(-5.*sin(t)*(5.*cos(t)-y(1))+5.*cos(t)*(5.*sin(t)-y(2)))*(5.*cos(t)-y(1))./((5.*cos(t)-y(1))^2+(5.*sin(t)-y(2))^2),

(-5.*sin(t)*(5.*cos(t)-y(1))+5.*cos(t)*(5.*sin(t)-y(2)))*(5.*sin(t)-y(2))./((5*cos(t)-y(1))^2+(5.*sin(t)-y(2))^2)];

clear,clc

close all

[t,y]=ode45('fun5',[0,100],[10,0]);

X=5.*cos(t);

Y=5.*sin(t);

figure(1)

plot(X,Y,'r.')

hold on

plot(y(:,1),y(:,2),'*')