Question

MATLAB求一阶导数为零时的参数值，怎么我求出来的是这个结果？求大神帮忙看看

syms A
>> F=(1687.091-493.477*tan(A)+151.956*sin(A))/(0.176+(1.732+tan(A))/(1.732*tan(A)-1)+(0.882+10*tan(A))/(19.981-7*tan(A)))

F =
((37989*sin(A))/250 - (4340669596320137*tan(A))/8796093022208 + 3709952343232479/2199023255552)/((tan(A) + 433/250)/((433*tan(A))/250 - 1) - (10*tan(A) + 441/500)/(7*tan(A) - 19981/1000) + 22/125)

>> F=diff(F)
F =
(((37989*sin(A))/250 - (4340669596320137*tan(A))/8796093022208 + 3709952343232479/2199023255552)*((10*tan(A)^2 + 10)/(7*tan(A) - 19981/1000) - (tan(A)^2 + 1)/((433*tan(A))/250 - 1) + ((tan(A) + 433/250)*((433*tan(A)^2)/250 + 433/250))/((433*tan(A))/250 - 1)^2 - ((10*tan(A) + 441/500)*(7*tan(A)^2 + 7))/(7*tan(A) - 19981/1000)^2))/((tan(A) + 433/250)/((433*tan(A))/250 - 1) - (10*tan(A) + 441/500)/(7*tan(A) - 19981/1000) + 22/125)^2 - ((4340669596320137*tan(A)^2)/8796093022208 - (37989*cos(A))/250 + 4340669596320137/8796093022208)/((tan(A) + 433/250)/((433*tan(A))/250 - 1) - (10*tan(A) + 441/500)/(7*tan(A) - 19981/1000) + 22/125)

>> a=solve(F,'A')
a =
2*atan(z) + 2*pi*k

Answer 1

应该用fzero（）函数来求解零点值。将程序如下，

syms A 

F=(1687.091-493.477*tan(A)+151.956*sin(A))/(0.176+(1.732+tan(A))/(1.732*tan(A)-1)+(0.882+10*tan(A))/(19.981-7*tan(A)))

Feq=diff(F)

Feq=@(A)eval(Feq);

[A,fval,exitflag] = fzero(Feq,rand())

求解结果