Check for missing argument or incorrect argument data type in call to function 'solve'.

Question

Arman Arman 2021-3-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/763586-check-for-missing-argument-or-incorrect-argument-data-type-in-call-to-function-solve

评论： Walter Roberson 2021-3-5

syms x1 x2 x3

Y=solve('4.4*x1-2.5*x2+19.2*x3-10.8*x4=4.3', '5.5*x1-9.3*x2-14.2*x3+13.2*x4=6.8', '7.1*x1-11.5*x2+5.3*x3-6.7*x4=-1.8', '14.2*x1+23.4*x2-8.8*x3+5.3*x4=7.2')

Check for missing argument or incorrect argument data type in call to function 'solve'.

why does it give an error?

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Answer 1

KSSV 2021-3-5

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https://ww2.mathworks.cn/matlabcentral/answers/763586-check-for-missing-argument-or-incorrect-argument-data-type-in-call-to-function-solve#answer_639711

编辑：KSSV 2021-3-5

在 MATLAB Online 中打开

syms x1 x2 x3 x4
eqn{1} = 4.4*x1-2.5*x2+19.2*x3-10.8*x4-4.3==0 ;
eqn{2} = 5.5*x1-9.3*x2-14.2*x3+13.2*x4-6.8==0 ;
eqn{3} = 7.1*x1-11.5*x2+5.3*x3-6.7*x4+1.8 ==0 ;
eqn{4} = 14.2*x1+23.4*x2-8.8*x3+5.3*x4-7.2==0 ; 
s = vpasolve(eqn{:}) ;
x1 = s.x1 ;
x2 = s.x2 ;
x3 = s.x3 ;
x4 = s.x4 ;

OR

syms x1 x2 x3 x4
Y=solve(4.4*x1-2.5*x2+19.2*x3-10.8*x4==4.3, 5.5*x1-9.3*x2-14.2*x3+13.2*x4==6.8, ......
        7.1*x1-11.5*x2+5.3*x3-6.7*x4==-1.8, 14.2*x1+23.4*x2-8.8*x3+5.3*x4==7.2)

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Walter Roberson 2021-3-5

Right.

The reason it gives an error is that that form of solve was supported until roughly r2017a, but has not been supported since then. Now only dsolve() supports quoted strings and that is expected to end soon.

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