Question

matlab解y关于x的二阶微分方程E*y+（h²/8π²m)*(d2y/dx2)=0 为什么解出来

Answer 1

syms E x y

>> y=dsolve('E*y+6.626e-34/8/pi^2/1.66e-27*D2y=0','x')

y =

C2*cos((100000000000000000000*pi*498945783132530120481927710843373^(1/2)*x*exp(1/2))/498945783132530120481927710843373) + C3*sin((100000000000000000000*pi*498945783132530120481927710843373^(1/2)*x*exp(1/2))/498945783132530120481927710843373)

>> vpa(y)

ans =

C2*cos(23188.381421487632207604131471235*x) + C3*sin(23188.381421487632207604131471235*x)

方程的解中含两个常数C2,C3,而没有C1,说明C1和E被某个数,C2或C3,替换了