Solve a system of non linear equations with parameters

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Rakesh Jain 2017-2-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/327098-solve-a-system-of-non-linear-equations-with-parameters

评论： Red_Devil_Box 2020-8-31

采纳的回答： Walter Roberson

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I have to find p11 p12 p22 in the following equations where q r b c are constants

p12^2/r + 2*c*p12 - 2*q = 0
p11 - b*p12 - c*p22 + (p12*p22)/r = 0
p22^2/r - 2*b*p22 + 2*p12 = 0

I specifically want to find p11 p12 and p22.

What should I do?

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采纳的回答

Walter Roberson 2017-2-27

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https://ww2.mathworks.cn/matlabcentral/answers/327098-solve-a-system-of-non-linear-equations-with-parameters#answer_256467

在 MATLAB Online 中打开

syms p12 r c q p11 b p22 
eqns = [p12^2/r + 2*c*p12 - 2*q ==0, p11 - b*p12 - c*p22 + (p12*p22)/r == 0, p22^2/r - 2*b*p22 + 2*p12 == 0]
sol = solve(eqns, [p11 p12 p22])
P11 = simplify(sol.p11,'steps',20);
P12 = simplify(sol.p12,'steps',20);
P22 = simplify(sol.p12,'steps',20);