Getting Empty sym: 0-by-1 when using solve function.

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I got a problem .It show "Empty sym: 0-by-1" in the function.I want to find x from this equation "eqn = (((x^2)/(2*R))-(x^2/4)-(1/(2*R))+(1/4))+(((x^2)/2)*(log(x)/log(exp(1))))-((k/(2*ro*ho))*((x^2)-((4*x^(1.5))/3)+(1/3)))-t" Any suggestions?
syms t R x k ro ho;
eqn = (((x^2)/(2*R))-(x^2/4)-(1/(2*R))+(1/4))+(((x^2)/2)*(log(x)/log(exp(1))))-((k/(2*ro*ho))*((x^2)-((4*x^(1.5))/3)+(1/3)))-t;
v_r = solve(eqn,x)

回答(1 个)

Walter Roberson
Walter Roberson 2021-1-20
There is no closed-form solution to that.
You will not even get closed form solutions if you substitute in constants for all of the variables other than x. If you do that, you still end up with an equation that has and . Some equations that have x or and have a closed form solution (involving Lambert's W function), but as soon as you get fractional powers of x, you have little hope of a closed form solution (not unless it happens that a change of variable can be done to rewrite in terms of first power of a variable and log of first power of the variable.)

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