matlab求解方程组时 Warning:Explicit solution could not be found.>

matlab求解方程组时 Warning:Explicit solution could not be found.> In solve at 170
syms u1 u2 u3 u4 u5 u6 u7 u8 u9 u10 u11 u12 u13 u14 u15 u16 u17 u18 u19 ;
u0=1;u20=1/2;h=0.05;
[u1,u2,u3,u4,u5,u6,u7,u8,u9,u10,u11,u12,u13,u14,u15,u16,u17,u18,u19]=...
solve('-1/h^2*(u2-2*u1+u0)+(1/(1+h)^2)*u1=-1/(1+h)^3',...
'-1/h^2*(u3-2*u2+u1)+(1/(1+2*h)^2)*u2=-1/(1+2*h)^3',...
'-1/h^2*(u4-2*u3+u2)+(1/(1+3*h)^2)*u3=-1/(1+3*h)^3',...
'-1/h^2*(u5-2*u4+u3)+(1/(1+4*h)^2)*u4=-1/(1+4*h)^3',...
'-1/h^2*(u6-2*u5+u4)+(1/(1+5*h)^2)*u5=-1/(1+5*h)^3',...
'-1/h^2*(u7-2*u6+u5)+(1/(1+6*h)^2)*u6=-1/(1+6*h)^3',...
'-1/h^2*(u8-2*u7+u6)+(1/(1+7*h)^2)*u7=-1/(1+7*h)^3',...
'-1/h^2*(u9-2*u8+u7)+(1/(1+8*h)^2)*u8=-1/(1+8*h)^3',...
'-1/h^2*(u10-2*u9+u8)+(1/(1+9*h)^2)*u9=-1/(1+9*h)^3',...
'-1/h^2*(u11-2*u10+u9)+(1/(1+10*h)^2)*u10=-1/(1+10*h)^3',...
'-1/h^2*(u12-2*u11+u10)+(1/(1+11*h)^2)*u11=-1/(1+11*h)^3',...
'-1/h^2*(u13-2*u12+u11)+(1/(1+12*h)^2)*u12=-1/(1+12*h)^3',...
'-1/h^2*(u12-2*u13+u12)+(1/(1+13*h)^2)*u13=-1/(1+13*h)^3',...
'-1/h^2*(u15-2*u14+u13)+(1/(1+14*h)^2)*u14=-1/(1+14*h)^3',...
'-1/h^2*(u16-2*u15+u14)+(1/(1+15*h)^2)*u15=-1/(1+15*h)^3',...
'-1/h^2*(u17-2*u16+u15)+(1/(1+16*h)^2)*u16=-1/(1+16*h)^3',...
'-1/h^2*(u18-2*u17+u16)+(1/(1+17*h)^2)*u17=-1/(1+17*h)^3',...
'-1/h^2*(u19-2*u18+u17)+(1/(1+18*h)^2)*u18=-1/(1+18*h)^3',...
'-1/h^2*(u20-2*u19+u18)+(1/(1+19*h)^2)*u19=-1/(1+19*h)^3');