# 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 Use 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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 syms Create symbolic scalar variables and functions, and matrix variables and functions sym Create symbolic variables, expressions, functions, matrices symfun Create symbolic functions symmatrix Create symbolic matrix variable symmatrix2sym Convert symbolic matrix variable to array of scalar variables symfunmatrix Create symbolic matrix function symfunmatrix2symfun Convert symbolic matrix function to symbolic function 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 or matrix function formula Return body of symbolic function or matrix 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