新手刚刚上手mathematica，在计算的时候发现矩阵求逆或者求特征值时，结果就和给的输入一样，没有计算，这是我哪里编错了还是个什么情况。
类似这几个图：
程序如下：
nl = 13
Nl = EYmod*h
Dl = EYmod*h^3/12
A2 = k22*G*h*(1 + h^2/(12*R^2))
A1 = Nl/R + Dl/(R^3)
u = 0
lK2 = 12.3
kl2 = K2*Dl*b/(2*R^3)
kl1 = kl2
kl3 = kl2
lk2 = lK2*Dl*b/(2*R^3)
lk1 = lk2
y1 = 2*Pi/nl
y2 = 0
y3 = y1
y0 = 0
nnd = 3
en = 1
m1c = 0
m2c = 0
m1s = 0
m2s = 0
cosm1 = 0
sinm1 = 0
cosm2 = 0
sinm2 = 0
m1c0 = 0
m1s0 = 0
m2c0 = 0
m2s0 = 0
Cn1 = -(nnd^2*A1 + A2/R)
Cn2 = nnd*(A1 + A2/R)
Cn3 = nnd^2*Dl/(R^2) + A2
Cn4 = -(A1 + nnd^2*A2/R)
Cn5 = nnd*(Dl/(R^2) + A2)
m1c1 = kl1*Cos[m*y1]*Cos[nnd*y1]
m1c2 = kl2*Cos[m*y2]*Cos[nnd*y2]
m1c3 = kl3*Cos[m*y3]*Cos[nnd*y3]
m2c1 = kl1*Sin[m*y1]*Cos[nnd*y1]
m2c2 = kl2*Sin[m*y2]*Cos[nnd*y2]
m2c3 = kl3*Sin[m*y3]*Cos[nnd*y3]
m1s1 = kl1*Cos[m*y1]*Sin[nnd*y1]
m1s2 = kl2*Cos[m*y2]*Sin[nnd*y2]
m1s3 = kl3*Cos[m*y3]*Sin[nnd*y3]
m2s1 = kl1*Sin[m*y1]*Sin[nnd*y1]
m2s2 = kl2*Sin[m*y2]*Sin[nnd*y2]
m2s3 = kl3*Sin[m*y3]*Sin[nnd*y3]
m1c = m1c + m1c1 + m1c2 + m1c3
m2c = m2c + m2c1 + m2c2 + m2c3
m1s = m1s + m1s1 + m1s2 + m1s3
m2s = m2s + m2s1 + m2s2 + m2s3
Cosm1 = Cos[m*y1]
Sinm1 = Sin[m*y1]
Cosm2 = Cos[m*y2]
Sinm2 = Sin[m*y2]
m1c0 = m1c0 + lk1*Cos[m*y0]*Cos[nnd*y0]
m1s0 = m1s0 + lk1*Cos[m*y0]*Sin[nnd*y0]
m2c0 = m2c0 + lk1*Sin[m*y0]*Cos[nnd*y0]
m2s0 = m2s0 + lk1*Sin[m*y0]*Sin[nnd*y0]
m1 = {{-p*h*R, 0, 0, 0, -p*h^3/12, 0},
{0, -p*h*R, 0, 0, 0, -p*h^3/12},
{0, 0, -p*h*R, 0, 0, 0},
{0, 0, 0, -p*h*R, 0, 0},
{-p*h^3/12, 0, 0, 0, -p*h^3*R/12, 0},
{0, -p*h^3/12, 0, 0, 0, -p*h^3*R/12}} // MatrixForm
M1 = {{p*h*R, 0, 0, 0, p*h^3/12, 0, 0, 0, 0, 0},
{0, p*h*R, 0, 0, 0, p*h^3/12, 0, 0, 0, 0},
{0, 0, p*h*R, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, p*h*R, 0, 0, 0, 0, 0, 0},
{p*h^3/12, 0, 0, 0, p*h^3*R/12, 0, 0, 0, 0, 0},
{0, p*h^3/12, 0, 0, 0, p*h^3*R/12, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, -ma, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, -ma, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0, -ma, 0},
{0, 0, 0, 0, 0, 0, 0, 0, 0, -M}} // MatrixForm
k1 = {{Cn1, 0, 0, Cn2, Cn3, 0},
{0, Cn1, -Cn2, 0, 0, Cn3},
{0, -Cn2, Cn4, 0, 0, Cn5},
{Cn2, 0, 0, Cn4, -Cn5, 0},
{Cn3, 0, 0, -Cn5, -Cn3*R, 0},
{0, Cn3, Cn5, 0, 0, -Cn3*R}} // MatrixForm
k2 = {{0, 0, m1c*u/(Pi*b), m2c*u/(Pi*b), 0, 0},
{0, 0, m1s*u/(Pi*b), m2s*u/(Pi*b), 0, 0},
{0, 0, -(m1c + m1c0)/(Pi*b), -(m2c + m2c0)/(Pi*b), 0, 0},
{0, 0, -(m1s + m1s0)/(Pi*b), -(m2s + m2s0)/(Pi*b), 0, 0},
{0, 0, -m1c*u*h/(2*Pi*b), -m2c*u*h/(2*Pi*b), 0, 0},
{0, 0, -m1s*u*h/(2*Pi*b), -m2s*u*h/(2*Pi*b), 0, 0}} // MatrixForm
k3 = {{-kl1*Cos[nnd*y1]*u/(Pi*b), -kl2*Cos[nnd*y2]*u/(Pi*b), -kl3*
Cos[nnd*y3]*u/(Pi*b), 0},
{-kl1*Sin[nnd*y1]*u/(Pi*b), -kl2*Sin[nnd*y2]*u/(Pi*b), -kl3*
Sin[nnd*y3]*u/(Pi*b), 0},
{kl1*Cos[nnd*y1]/(Pi*b), kl2*Cos[nnd*y2]/(Pi*b),
kl3*Cos[nnd*y3]/(Pi*b), lk1*Cos[nnd*y0]/(Pi*b)},
{kl1*Sin[nnd*y1]/(Pi*b), kl2*Sin[nnd*y2]/(Pi*b),
kl3*Sin[nnd*y3]/(Pi*b), lk1*Sin[nnd*y0]/(Pi*b)},
{kl1*Cos[nnd*y1]*u*h/(2*Pi*b), kl2*Cos[nnd*y2]*u*h/(2*Pi*b),
kl3*Cos[nnd*y3]*u*h/(2*Pi*b), 0},
{kl1*Sin[nnd*y1]*u*h/(2*Pi*b), kl2*Sin[nnd*y2]*u*h/(2*Pi*b),
kl3*Sin[nnd*y3]*u*h/(2*Pi*b), 0}} // MatrixForm
k411 = {{Cn1, 0, m1c*u/(Pi*b), Cn2 + m2c*u/(Pi*b), Cn3, 0},
{0, Cn1, -Cn2 + m1s*u/(Pi*b), m2s*u/(Pi*b), 0, Cn3},
{0, -Cn2, Cn4 + -(m1c + m1c0)/(Pi*b), -(m2c + m2c0)/(Pi*b), 0, Cn5},
{Cn2, 0, -(m1s + m1s0)/(Pi*b), Cn4 - (m2s + m2s0)/(Pi*b), -Cn5, 0},
{Cn3, 0, -m1c*u*h/(2*Pi*b), -Cn5 - m2c*u*h/(2*Pi*b), -Cn3*R, 0},
{0, Cn3, Cn5 - m1s*u*h/(2*Pi*b), -m2s*u*h/(2*Pi*b), 0, -Cn3*R}} //
MatrixForm
k4 = {{Cn1, 0, m1c*u/(Pi*b), Cn2 + m2c*u/(Pi*b), Cn3,
0, -kl1*Cos[nnd*y1]*u/(Pi*b), -kl2*Cos[nnd*y2]*u/(Pi*b), -kl3*
Cos[nnd*y3]*u/(Pi*b), 0},
{0, Cn1, -Cn2 + m1s*u/(Pi*b), m2s*u/(Pi*b), 0,
Cn3, -kl1*Sin[nnd*y1]*u/(Pi*b), -kl2*Sin[nnd*y2]*u/(Pi*b), -kl3*
Sin[nnd*y3]*u/(Pi*b), 0},
{0, -Cn2, Cn4 + -(m1c + m1c0)/(Pi*b), -(m2c + m2c0)/(Pi*b), 0, Cn5,
kl1*Cos[nnd*y1]/(Pi*b), kl2*Cos[nnd*y2]/(Pi*b),
kl3*Cos[nnd*y3]/(Pi*b), lk1*Cos[nnd*y0]/(Pi*b)},
{Cn2, 0, -(m1s + m1s0)/(Pi*b), Cn4 - (m2s + m2s0)/(Pi*b), -Cn5, 0,
kl1*Sin[nnd*y1]/(Pi*b), kl2*Sin[nnd*y2]/(Pi*b),
kl3*Sin[nnd*y3]/(Pi*b), lk1*Sin[nnd*y0]/(Pi*b)},
{Cn3, 0, -m1c*u*h/(2*Pi*b), -Cn5 - m2c*u*h/(2*Pi*b), -Cn3*R, 0,
kl1*Cos[nnd*y1]*u*h/(2*Pi*b), kl2*Cos[nnd*y2]*u*h/(2*Pi*b),
kl3*Cos[nnd*y3]*u*h/(2*Pi*b), 0},
{0, Cn3, Cn5 - m1s*u*h/(2*Pi*b), -m2s*u*h/(2*Pi*b), 0, -Cn3*R,
kl1*Sin[nnd*y1]*u*h/(2*Pi*b), kl2*Sin[nnd*y2]*u*h/(2*Pi*b),
kl3*Sin[nnd*y3]*u*h/(2*Pi*b), 0}} // MatrixForm
k5 = {{0, 0, -kl1*Cosm1, -kl1*Sinm1, 0, 0, 2*kl1, 0, 0, 0},
{0, 0, -kl2*Cosm2, -kl2*Sinm2, 0, 0, 0, 2*kl2, 0, 0},
{0, 0, -kl3*Cosm1, -kl3*Sinm1, 0, 0, 0, 0, 2*kl3, 0},
{0, 0, -lk1*Cosm2, -lk1*Sinm2, 0, 0, 0, 0, 0, lk1 + lk2}} //
MatrixForm
K = Join[k4, k5, 2]
A = Inverse[-M1]*K
Eigenvalues[A]

刚刚那位大神哪去了。。EYMOD是我设置的一个变量，MMA的变量设置是不能大写吗？

把M1表达式后面的// MatrixForm删掉就好了
具体原因我也不清楚,可能和吧主之前有提到过的使用MatrixForm后表达式会被嵌套一层东西有关