>> fe=0:0.01:0.6;
ap=0.2;
k=2000;
cf=200;
kr=45*pi/180;
kr1=30*pi/180;
h=0.25;
kc=cf*(fe*sin(kr)).^(-0.25);
u=1-fe*sin(kr)*sin(kr1)/(sin(kr+kr1)*ap);
blim=2*k*h.^2*(1+((1-u.^2)+u.^2/h.^2).^0.5)/(kc*u.^2);
plot(blim,fe);
??? Error using ==> *
Inner matrix dimensions must agree.

错误说你的矩阵维数不统一，你看下你的矩阵是不是因为无法运算而报错啊

blim=2*k*h.^2*(1+((1-u.^2)+u.^2/h.^2).^0.5)/(kc*u.^2);
改成
blim=2*k*h.^2*(1+((1-u.^2)+u.^2/h.^2).^0.5)./(kc.*u.^2);