Question

matlab作图问题

为了实现多函数图像出现在同一坐标系下，我编写了如下程序：
x1=22:1:35;
y1=-515001.0900+61846.4900*x-2277.4190*(x^2)+27.8248*(x^3);
x2=22:1:35;
y2=-664391.0787+79475.7697*x-2964.4358*x^2+36.6668*x^3;
x3=0:1:35;
y3=28213.4156+1077.1023*x-242.5052*x^2+26.1884*x^3-1.0287*x^4+0.0134*x^5;
x4=0:1:35;
y4=28301.4666+1007.0263*x-227.7576*x^2+24.9751*x^3-0.9864*x^4+0.0129*x^5;
plot(x1,y1,x2,y2,x3,y3,x4,y4,);
出现以下错误：
??? Error: File: Untitled.m Line: 9 Column: 30
Unbalanced or unexpected parenthesis or bracket.
请高手指点。。。。。。。。。。。。

Answer 1

1）无需定义过多变量
定义一个x=22:1:35;即可。

2）注意向量的乘积用“点乘”
y1=-515001.0900+61846.4900*x-2277.4190*(x.^2)+27.8248*(x.^3);
y2=-664391.0787+79475.7697*x-2964.4358*x.^2+36.6668*x.^3;
y3=28213.4156+1077.1023*x-242.5052*x.^2+26.1884*x.^3-1.0287*x.^4+0.0134*x.^5;
y4=28301.4666+1007.0263*x-227.7576*x.^2+24.9751*x.^3-0.9864*x.^4+0.0129*x.^5;

3)将x1、x2……换成x即可，然后你的plot函数里面后边多个逗号
plot(x,y1,x,y2,x,y3,x,y4);

*）综上：
x=22:1:35;

y1=-515001.0900+61846.4900*x-2277.4190*(x.^2)+27.8248*(x.^3);
y2=-664391.0787+79475.7697*x-2964.4358*x.^2+36.6668*x.^3;
y3=28213.4156+1077.1023*x-242.5052*x.^2+26.1884*x.^3-1.0287*x.^4+0.0134*x.^5;
y4=28301.4666+1007.0263*x-227.7576*x.^2+24.9751*x.^3-0.9864*x.^4+0.0129*x.^5;

plot(x,y1,x,y2,x,y3,x,y4);

Answer 2

x1=22:1:35;
y1=-515001.0900+61846.4900*x1-2277.4190*(x1.*x1)+27.8248*(x1.*x1.*x1);
x2=22:1:35;
y2=-664391.0787+79475.7697*x2-2964.4358*(x2.*x2)+36.6668*(x2.*x2.*x2);
x3=0:1:35;
y3=28213.4156+1077.1023*x3-242.5052*(x3.*x3)+26.1884*(x3.*x3.*x3)-1.0287*(x3.*x3.*x3.*x3)+0.0134*(x3.*x3.*x3.*x3.*x3);
x4=0:1:35;
y4=28301.4666+1007.0263*x4-227.7576*(x4.*x4)+24.9751*(x4.*x4.*x4)-0.9864*(x4.*x4.*x4.*x4)+0.0129*(x4.*x4.*x4.*x4.*x4);
plot(x1,y1);
hold on
plot(x2,y2);
plot(x3,y3);
plot(x4,y4);
学会用hold on啊。
还有我按自己的的猜测把你的x全换了。
而且向量是不能平方的，必须写成x1.*x1.