求解答：matlab中分段函数问题symsuf=-2*u.^4+2*u.^2+u/6+0.3;ifu>=(-0.9-f(-0.9))&u<=(-0.9)g=0.9+u+f(-0.9);elseifu>=(-0.9)&u<=1g=f;elseifu>=1&u<=(1+f(1))g=1-u-f(1);end

Question

求解答：matlab中分段函数问题

syms u 

f=-2*u.^4+2*u.^2+u/6+0.3;

if u >= (-0.9-f(-0.9)) & u <= (-0.9)

    g =0.9+u+f(-0.9);

else if u>=(-0.9) & u<=1

    g=f;

    else if u>=1 & u<=(1+f(1))

    g=1-u-f(1);

        end

    end

end

求大神帮忙看看哪里出错了?是分段函数写的不对还是 syms 的缘故?

Answer 1

这样就对了：
>> f = @(u) -2*u.^4+2*u.^2+u/6+0.3;
>> g = @(u) (u>= -0.9-f(-0.9) & u <= -0.9).*(0.9 + u+f(-0.9)) + (u>= -0.9 & u<=1).*f(u) + (u>=1 & u<=1+f(1)).*(1-u-f(1))
g = 
    @(u)(u>=-0.9-f(-0.9)&u<=-0.9).*(0.9+u+f(-0.9))+(u>=-0.9&u<=1).*f(u)+(u>=1&u<=1+f(1)).*(1-u-f(1))
>> plot(linspace(-1,1,100),g(linspace(-1,1,100)))