solve a vector of independent equations with only one variable

Question

Pooneh Shah Malekpoor 2021-2-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/749057-solve-a-vector-of-independent-equations-with-only-one-variable

回答： Walter Roberson 2021-2-18

Hello

Could anyone please guide me as to how solve this system of vector equations(EQ), so it would give me a vector of solutions for d? I just get 0!!!It is worthy to note that phi and n are double parameters and beta(i) is a vector of numbers defined previously.

    syms d   
        QQ=sym(zeros(n,1));
          i=1:n;
              EQ = cos(beta(i))+(((sin(beta(i)))*tan(phi*pi/180))/d)-0.2;
              QQ=solve(EQ,d,'Real',true);

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Answer 1

Walter Roberson 2021-2-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/749057-solve-a-vector-of-independent-equations-with-only-one-variable#answer_626772

在 MATLAB Online 中打开

EQ = cos(beta(i))+(((sin(beta(i)))*tan(phi*pi/180))/d)-0.2;

Your beta and phi are constants, and the implied equation for solve is that the value must equal 0. So we have

== cos(beta(i))+(((sin(beta(i)))*tan(phi*pi/180))/d)-0.2
2 == cos(beta(i)) + (((sin(beta(i)))*tan(phi*pi/180))/d)
2 - cos(beta(i)) == sin(beta(i)))*tan(phi*pi/180) / d
d = sin(beta(i)))*tan(phi*pi/180) / (0.2 - cos(beta(i)))

Giving you the vectorized calculation

d = sin(beta) .* tan(phi*pi/180) ./ (0.2 - cos(beta));

No solve() needed.