The second argument must be a vector of symbolic variables

y=solve(I*x == zeros(3,1) , x .* x ==x , 'ReturnConditions', true)
Error using sym.getEqnsVars>checkVariables (line 92)
The second argument must be a vector of symbolic variables.

Can someone explain to me what is wrong with this?

Answer 1

[Walter Roberson]

You can use one array or vector of equations, or you can use multiple individual equations, but you cannot use multiple arrays or vectors of equations. You will need to construct a single array or vector from the parts.

[Bilal sadiq]

Walter Roberson crap what a answer you have given.................pathetic you just translated matlab error ,,,,,,,,,,,,,,provide solution for help crap man

[Walter Roberson]

"you just translated matlab error"

I disagree.

The syntax documentation https://www.mathworks.com/help/symbolic/solve.html#buezrr6-eqns is not completely clear as to how to enter a system of equations. If one followed the conventions of the rest of the MATLAB documentation, the implication of the documented syntaxes would be that a system of equations would have to be entered as a vector or array, but the documentation has an explicit example at https://www.mathworks.com/help/symbolic/solve.html#buezrr6-ReturnConditions showing that multiple equations can be entered as separate arguments (which was the situation historically.) And historically, the closely related dsolve() permitted a separate argument for the initial conditions compared to the equations

It was thus entirely reasonable for the user "Standardtrickyness" to have attempted to pass multiple arguments of equations. I had to dig into the solver code to establish that you can either pass individual equations as separate arguments (historical arrangement) or you can pass an array or vector of equations (what the large majority of the current documentation uses), but that you cannot do both. My memory from last year is that it took me about 25 minutes of debugging of the Mathworks code to work out what was and was not permitted.

"provide solution for help"

You will need to construct a single array or vector from the parts.

For example, instead of

y=solve(I*x == zeros(3,1) , x .* x ==x , 'ReturnConditions', true)

you could use

eqn1 = I*x == zeros(3,1);
eqn2 = x .* x ==x;
y = solve( [eqn1(:); eqn2(:)], 'ReturnConditions', true)

[Standardtrickyness]

thanks