# Simplify Symbolic Expression

Simplify symbolic expressions in Live Editor

Since R2020a

## Description

• Perform algebraic simplification of symbolic expressions.

• Rewrite expressions in terms of another function.

• Expand algebraic expressions.

• Combine terms of identical algebraic structure.

• Generate the code used to simplify or rearrange expressions.

### Related Functions

The code that Simplify Symbolic Expression generates to simplify expressions uses these functions.

To add the Simplify Symbolic Expression task to a live script in the MATLAB Editor:

• On the Live Editor tab, select Task > Simplify Symbolic Expression.

• In a code block in your script, type a relevant keyword, such as simplify, symbolic, rewrite, expand, or combine. Select Simplify Symbolic Expression from the suggested command completions.

## Parameters

expand all

Specify the simplification method from the drop-down list:

Simplification MethodDescription
SimplifyPerform algebraic simplification.
Simplify fractionSimplify symbolic rational expressions.
RewriteRewrite expressions in terms of another function.
ExpandExpand expressions and simplify inputs of functions by using identities.
CombineCombine terms of identical algebraic structure.

Specify the computational effort used for the Simplify method from the drop-down list:

Simplification EffortDescription
MinimumMinimum effort with fastest computation time (can return most complicated result)
LowLow effort with faster computation time
MediumMedium effort with normal computation time
HighHigh effort with slower computation time
FullFull effort with slowest computation time (can return simplest result)

Select this check box to not expand special functions for the Expand method. This option expands the arithmetic part of an expression, such as powers and roots, without expanding trigonometric, hyperbolic, logarithmic, and special functions.

Select this check box to apply purely algebraic simplifications to the Expand method, such as log(a) + log(b) = log(a*b) with the assumption that a and b are real positive numbers. Setting Ignore analytic constraints to on can give you simpler solutions, which could lead to results not generally valid. This option applies mathematical identities that are convenient for most engineering workflow, but do not always hold for all values of variables. In some cases, this option can lead to simpler results that are not equivalent to the initial expression. For details, see Algorithms.

## Algorithms

When you use Ignore analytic constraints, then the simplification follows some of these rules:

• log(a) + log(b) = log(a·b) for all values of a and b. In particular, the following equality is valid for all values of a, b, and c :

(a·b)c = ac·bc.

• log(ab) = b·log(a) for all values of a and b. In particular, the following equality is valid for all values of a, b, and c :

(ab)c = ab·c.

• If f and g are standard mathematical functions and f(g(x)) = x for all small positive numbers, f(g(x)) = x is assumed to be valid for all complex values of x. In particular:

• log(ex) = x

• asin(sin(x)) = x, acos(cos(x)) = x, atan(tan(x)) = x

• asinh(sinh(x)) = x, acosh(cosh(x)) = x, atanh(tanh(x)) = x

• Wk(x·ex) = x for all branch indices k of the Lambert W function.

## Version History

Introduced in R2020a