solving algebraic equations and characteristic vectors

I am very new in matlab. I am struggling with warnings when I am trying to solve algebraic equaions. Would you please help me understand the situation?

When I do this operation: >> solve('x^2-5*x+6=0')

I take this warning, and I don't understand anything from it. What is character vector here?

1. Warning: Support of character vectors will be removed in a future release. Character vectors can be used only for variable names and numbers. Instead, to create

What is characteristic vector here?

2.symbolic expressions first create symbolic variables using 'syms'. To evaluate character vectors and strings representing symbolic expressions, use 'str2sym'.

What does 2 says?

> In sym>convertExpression (line 1581)

In sym>convertChar (line 1486)

In sym>tomupad (line 1236)

In sym (line 215)

In solve>getEqns (line 406)

In solve (line 226)

Warning: Do not specify equations and variables as character vectors. Instead, create symbolic variables with syms.

> In solve>getEqns (line 446)

In solve (line 226)

Answer 1

[Stephan]

Try:

syms x
sol = solve(x^2-5*x+6==0)

Character is a data type that is defined by '...' like you did. For symbolic expressions in future releases this support will be removed.

If you want to solve symbolic expressions you need to tell matlab what the symbolic variables are. For that use syms command.

[metin yilmaz]

Thank you but how many times shoud I enter syms command? In every new equation?

[Stephan]

Only once

Answer 2

[Star Strider]

The term MATLAB uses here is ‘character’, not ‘characteristic’.

A character vector is a vector make up of ASCII characters defined by single quotes at the beginning and end of the vector (see the char function).

This will do what you want, and not throw the warning:

syms x 
xs = solve(x^2-5*x+6==0)

.

[Star Strider]

Enter the syms command only once, when you first need to declare the variables.

You will need to do that each time you begin a new session with the Sybolic Math Toolbox.

Answer 3

[metin yilmaz]

How many times should I enter syms command? In every new equation?