I tried all day to run my code syms R t; eqn = Rtan(10022.99039R)-(6.9796410^-3sqrt(t))/R==0 ; m = linspace(10,20,1) ; sol = zeros(size(t)) ; for i =1 :length(m) eqn = subs(eqn,t,m(i)) ; sol(i) = double(solve(eqn,R)) ; end plot(m,sol)

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alburary daniel 2018-6-10

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关闭： alburary daniel 2018-6-13

this is my code

syms R t;
eqn = R*tan(10022.99039*R)-(6.97964*10^-3*sqrt(t))/R==0 ;
m = linspace(10,20,1) ;
sol = zeros(size(t)) ;
for i =1 :length(m)
    eqn = subs(eqn,t,m(i)) ;
    sol(i) = double(solve(eqn,R)) ;
end
plot(m,sol)

But when I running matlab give me the following issues

Error using mupadmex
Internal error with symbolic engine. Quit and restart MATLAB.
Error in sym>cell2ref (line 1303)
S = mupadmex(y);
Error in sym>tomupad (line 1241)
    S = cell2ref(numeric2cellstr(x));
Error in sym (line 215)
                S.s = tomupad(x);
Error in syms (line 197)
toDefine = sym(zeros(1, 0));
Error in SOLUCION1 (line 3)
syms R t;

any suggetion?

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Answer 1

Ameer Hamza 2018-6-10

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It seems that there is some problem with symbolic math toolbox. If you are using R2017b or R2018a on windows 10 then you might try this recent update: https://www.mathworks.com/support/bugreports/1755918.

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Ameer Hamza 2018-6-12

在 MATLAB Online 中打开

You are getting this warning because the analytical solution of this equation does not exist. In this non-linear equation, you cannot write a closed form solution of the form

R = f(t)

where f is an analytical function. Therefore, MATLAB gives this warning and return a numeric solution instead.

Walter Roberson 2018-6-12

There are an infinite number of solutions. The normal value of the function is about -1E47, so you only get a zero of the function when tan(10022.99039*R) approaches infinity close enough to overcome the -1E47. The function is highly non-linear there, so finding the correct value is difficult.