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# Symbolic Variables, Expressions, Functions, and Preferences

Create symbolic variables, expressions, functions, and set preferences

Symbolic Math Toolbox™ introduces a special data type — symbolic objects. This data type includes symbolic numbers, symbolic variables, symbolic expressions, and symbolic functions. It also includes vectors, matrices, and multidimensional arrays of symbolic numbers, variables, expressions, and functions. Using symbolic objects in computations indicates that MATLAB® must perform these computations analytically instead of numerically. Symbolic computations are exact and are not prone to round-off errors. For more details about symbolic objects, see Symbolic Objects to Represent Mathematical Objects. For a quick guide on creating symbolic variables, expressions, and functions, see Create Symbolic Numbers, Variables, and Expressions and Create Symbolic Functions.

## Functions

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 `sym` Create symbolic variables, expressions, functions, matrices `syms` Create symbolic scalar variables, functions, and matrix variables `symfun` Create symbolic functions `symmatrix` Create symbolic matrix variable `symmatrix2sym` Convert symbolic matrix variable to array of scalar variables `str2sym` Evaluate string representing symbolic expression `fold` Combine (fold) vector using function `piecewise` Conditionally defined expression or function
 `symvar` Find symbolic variables in symbolic input `argnames` Input variables of symbolic function `formula` Return body of symbolic function `has` Check if expression contains particular subexpression `children` Subexpressions or terms of symbolic expression
 `symType` Determine type of symbolic object `symFunType` Determine functional type of symbolic object `isSymType` Determine whether symbolic object is specific type `hasSymType` Determine whether symbolic object contains specific type `findSymType` Find symbolic subobjects of specific type `mapSymType` Apply function to symbolic subobjects of specific type
 `isfinite` Check whether symbolic array elements are finite `isinf` Check whether symbolic array elements are infinite `isnan` Check whether symbolic array elements are `NaN`s
 `sympref` Set symbolic preferences

## Topics

Create Symbolic Numbers, Variables, and Expressions

Use symbolic values and variables.

Create Symbolic Functions

Use symbolic functions that accept symbolic inputs, such as `f(x,y)`.

Create Symbolic Matrices

Use matrices containing symbolic values.

Create Symbolic Matrix Variables

Use symbolic matrix variables.

Symbolic Objects to Represent Mathematical Objects

Use symbolic objects to represent mathematical objects.

Find Symbolic Variables in Expressions, Functions, Matrices

Find variables in symbolic expressions.

Choose syms or sym Function

Choose `syms` or `sym` function.

Change Output Display Format of Symbolic Results in the Live Editor

Modify output of symbolic results.

Add Subscripts, Superscripts, and Accents to Symbolic Variables in the Live Editor

Add suffixes to symbolic variables.

Copy and Paste Symbolic Output in Live Editor

Copy and paste symbolic output.

## Support

#### Mathematical Modeling with Symbolic Math Toolbox

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