在MATLAB中该怎么利用成程序解F=K*theta/((a+0.5*l)*sin(pi-theta))中的theta表

问题描述:

在MATLAB中该怎么利用成程序解F=K*theta/((a+0.5*l)*sin(pi-theta))中的theta表达式
1个回答 分类:综合 2014-09-27

问题解答:

我来补答
solve('F=K*theta/((a+0.5*l)*sin(pi-theta))','theta')
Error using ==> solve
Unable to find closed form solution.
虽然求不出准确的表达式,但是近似的还是可以求出来的,请看下面:
>> syms theta
>> taylor(sin(pi-theta))
ans =
theta-1/6*theta^3+1/120*theta^5 %用泰勒展开近似表示sin(pi-theta)
然后用solve()求解的结果为:
>> solve('F=K*theta/((a+0.5*l)*(theta-1/6*theta^3+1/120*theta^5))','theta')
ans =
1.4142135623730950488016887242097/(2.*F*a+F*l)*(F*(2.*a+l)*(10.*F*a+5.*F*l+(-20.*F^2*a^2-20.*F^2*a*l-5.*F^2*l^2+120.*F*a*K+60.*F*l*K)^(1/2)))^(1/2)
-1.4142135623730950488016887242097/(2.*F*a+F*l)*(F*(2.*a+l)*(10.*F*a+5.*F*l+(-20.*F^2*a^2-20.*F^2*a*l-5.*F^2*l^2+120.*F*a*K+60.*F*l*K)^(1/2)))^(1/2)
1.4142135623730950488016887242097/(2.*F*a+F*l)*(F*(2.*a+l)*(-1.*(-20.*F^2*a^2-20.*F^2*a*l-5.*F^2*l^2+120.*F*a*K+60.*F*l*K)^(1/2)+10.*F*a+5.*F*l))^(1/2)
-1.4142135623730950488016887242097/(2.*F*a+F*l)*(F*(2.*a+l)*(-1.*(-20.*F^2*a^2-20.*F^2*a*l-5.*F^2*l^2+120.*F*a*K+60.*F*l*K)^(1/2)+10.*F*a+5.*F*l))^(1/2)
这个结果有点令人蛋疼.眼晕!
 
 
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