matlab微分方程组求解方程组:dx/dt=-2Ax+uydy/dt=2Ax+auz-(A+u)yx+y+z=1matlab求解如下:>>global A,u>>[x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','x+y+z=1','x(0)=1,y(0)=0,z(0)=0')结果出错:Error using ==> dsolveThere ar
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![matlab微分方程组求解方程组:dx/dt=-2Ax+uydy/dt=2Ax+auz-(A+u)yx+y+z=1matlab求解如下:>>global A,u>>[x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','x+y+z=1','x(0)=1,y(0)=0,z(0)=0')结果出错:Error using ==> dsolveThere ar](/uploads/image/z/399348-36-8.jpg?t=matlab%E5%BE%AE%E5%88%86%E6%96%B9%E7%A8%8B%E7%BB%84%E6%B1%82%E8%A7%A3%E6%96%B9%E7%A8%8B%E7%BB%84%EF%BC%9Adx%2Fdt%3D-2Ax%2Buydy%2Fdt%3D2Ax%2Bauz-%28A%2Bu%29yx%2By%2Bz%3D1matlab%E6%B1%82%E8%A7%A3%E5%A6%82%E4%B8%8B%EF%BC%9A%3E%3Eglobal+A%2Cu%3E%3E%5Bx%2Cy%2Cz%5D%3Ddsolve%28%27Dx%3D%28-2%29%2AA%2Ax%2Bu%2Ay%27%2C%27Dy%3D2%2AA%2Ax%2B2%2Au%2Az-%28A%2Bu%29%2Ay%27%2C%27x%2By%2Bz%3D1%27%2C%27x%280%29%3D1%2Cy%280%29%3D0%2Cz%280%29%3D0%27%29%E7%BB%93%E6%9E%9C%E5%87%BA%E9%94%99%EF%BC%9AError+using+%3D%3D%3E+dsolveThere+ar)
matlab微分方程组求解方程组:dx/dt=-2Ax+uydy/dt=2Ax+auz-(A+u)yx+y+z=1matlab求解如下:>>global A,u>>[x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','x+y+z=1','x(0)=1,y(0)=0,z(0)=0')结果出错:Error using ==> dsolveThere ar
matlab微分方程组求解
方程组:dx/dt=-2Ax+uy
dy/dt=2Ax+auz-(A+u)y
x+y+z=1
matlab求解如下:
>>global A,u
>>[x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','x+y+z=1','x(0)=1,y(0)=0,z(0)=0')
结果出错:
Error using ==> dsolve
There are more ODEs than variables.
为什么会出错?
matlab微分方程组求解方程组:dx/dt=-2Ax+uydy/dt=2Ax+auz-(A+u)yx+y+z=1matlab求解如下:>>global A,u>>[x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','x+y+z=1','x(0)=1,y(0)=0,z(0)=0')结果出错:Error using ==> dsolveThere ar
把第三个式子也微分.
>> [x,y,z]=dsolve('Dx=(-2)*A*x+u*y','Dy=2*A*x+2*u*z-(A+u)*y','Dx+Dy+Dz=0','x(0)=1,y(0)=0,z(0)=0')
x =
u^2/(A^2+2*u*A+u^2)+2*u*A/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)
y =
-(-2*u*A^2/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+2*u^2*A/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+2*A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)*u-2*A*u^2/(A^2+2*u*A+u^2))/u
z =
(-2*u^2*A^2/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)*u^2+A^2*u^2/(A^2+2*u*A+u^2))/u^2
>> test=x+y+z
test =
u^2/(A^2+2*u*A+u^2)+2*u*A/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)-(-2*u*A^2/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+2*u^2*A/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+2*A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)*u-2*A*u^2/(A^2+2*u*A+u^2))/u+(-2*u^2*A^2/(A^2+2*u*A+u^2)*exp(-(A+u)*t)+A^2/(A^2+2*u*A+u^2)*exp(-2*(A+u)*t)*u^2+A^2*u^2/(A^2+2*u*A+u^2))/u^2
>> simplify(test)
ans =
1
a小写??