Question

求解决MATLAB问题，急

syms v n c g Pi R a
f=(60/n-Pi*R/30/g*n-0.2-(2*(a*v/6/n-v^2/2/c+v^2/2/g)/g)^0.5)*6*n-a;
s=solve(f,a)
总是出现以下错误提示

Warning: List of equations is empty.
> In solve at 87
??? Undefined function or variable 'a'.

Answer 1

我用的是2011b得到的结果:
你是不是用6.5绿色的

syms v n c g Pi R a
f=(60/n-Pi*R/30/g*n-0.2-(2*(a*v/6/n-v^2/2/c+v^2/2/g)/g)^0.5)*6*n-a;
s=solve(f,a)

s =

(1800*g - 6*g*n + 30*n*v + 90*n^2*(-(v*(6*c*g*n - 1800*c*g - 30*c*n*v + 15*g*n*v + Pi*R*c*n^2))/(135*c*n^3))^(1/2) - Pi*R*n^2)/(5*g)
-(6*g*n - 1800*g - 30*n*v + 90*n^2*(-(v*(6*c*g*n - 1800*c*g - 30*c*n*v + 15*g*n*v + Pi*R*c*n^2))/(135*c*n^3))^(1/2) + Pi*R*n^2)/(5*g)

Answer 2

可以求解的，我用的是7.1
syms v n c g Pi R a
f=(60/n-Pi*R/30/g*n-0.2-(2*(a*v/6/n-v^2/2/c+v^2/2/g)/g)^0.5)*6*n-a;
s=solve(f,a)

s =
-1/5*(-1800*g+pi*R*n^2+6*n*g+3^(1/2)/c*(-10*v*c*3^(1/2)*n+2*(150*v^2*c^2*n^2+9000*n*c^2*v*g-5*n^3*c^2*v*pi*R-30*n^2*c^2*v*g-75*n^2*c*v^2*g)^(1/2)))/g
-1/5*(-1800*g+pi*R*n^2+6*n*g+3^(1/2)/c*(-10*v*c*3^(1/2)*n-2*(150*v^2*c^2*n^2+9000*n*c^2*v*g-5*n^3*c^2*v*pi*R-30*n^2*c^2*v*g-75*n^2*c*v^2*g)^(1/2)))/g