How to solve multiple equations

Question

HUH 2014-11-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/164139-how-to-solve-multiple-equations

评论： HUH 2014-11-24

This should be simple, but will someone show how to solve these two equations for A12 and A21. I can't understand the syms or solve commands

x1_a=.1
x2_a=1-x1_a
x1_b=.9
x2_b=1-x1_b
%gamma1_a=exp(x2_a^2*(A12+2*(A21-A12)*x1_a))
%gamma2_a=exp(x1_a^2*(A21+2*(A12-A21)*x2_a))
%gamma1_b=exp(x2_b^2*(A12+2*(A21-A12)*x1_b))
%gamma2_b=exp(x1_b^2*(A21+2*(A12-A21)*x2_b))
x1_a*(exp(x2_a^2*(A12+2*(A21-A12)*x1_a)))= x1_b*(exp(x2_b^2*(A12+2*(A21-A12)*x1_b)))
x2_a*(exp(x1_a^2*(A21+2*(A12-A21)*x2_a)))= x2_b*(exp(x1_b^2*(A21+2*(A12-A21)*x2_b)))

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Answer 1

Roger Stafford 2014-11-24

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/164139-how-to-solve-multiple-equations#answer_160112

在 MATLAB Online 中打开

Consult these two sites carefully:

   http://www.mathworks.com/help/symbolic/syms.html
   http://www.mathworks.com/help/symbolic/solve.html

However, in your particular equations I would take the logarithm of both sides of each equation, which would produce linear equations in the two unknowns, and which Matlab can therefore easily solve.