# Type::RatExpr

Type representing rational expressions

### Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

## Syntax

```testtype(`obj`, Type::RatExpr(`indet`, <`coeff_type`>))
```

## Description

With `Type::RatExpr`, rational expressions can be identified.

The call `testtype(obj, Type::RatExpr(indet))` checks, whether `obj` is a rational expression in the indeterminante `indet`, i.e., the quotient of two polynomial expressions in `indet`. If it is, the result is `TRUE`, otherwise `FALSE`.

A rational expression in `indet` is a expression, and `indet` occurs only as operand of `_plus` or `_mult` expressions and in `_power` with an integer exponent.

`indet` must be an identifier, and `coeff_type` a type for the coefficients of the rational expression.

This type does not represent a property.

## Examples

### Example 1

A polynomial expression in `x` is also a rational expression in `x`:

`testtype(-x^2 - x + 3, Type::RatExpr(x))`

`testtype` is used to select all rational operands in `x` with positive integer coefficients:

```EX := sin(x) + x^2 - 3*x + 2 + 3/x: select(EX, testtype, Type::RatExpr(x, Type::PosInt))```

`delete EX:`

## Parameters

 `obj` Any MuPAD® object `indet` An indeterminante `coeff_type` A type for the coefficientes; a type can be an object of the library Type or one of the possible return values of `domtype` and `type`