[shirleyflh]

这是求曲率最大点的程序,我单步运行可通过,结果正确,但整体一起运行就出错,错误是
?? Error using ==> ./
Matrix dimensions must agree.

Error in ==> D:\lianghua\matlabwork\cequlv.m
On line 9 ==> k1b=k2./(((1+k1.^2)).^(3/2))

请教 是为什么?怎么解决?

程序如下:
syms x y21
y21='5*x^2+5'
k2=diff(y21,2)
k1=diff(y21,1)

k1b=k2./(((1+k1.^2)).^(3/2))
k1b=abs(k1b)

x=-11:20

k1=subs(k1b)
k1=double(k1)
nk1=length(k1)
maxk1=max(k1)
[mk1,nk1]=find(k1==maxk1)

plot(x,y,x(nk1),y(nk1),'r.')