# 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 NaNs
 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