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# Type::Negative

Type and property representing negative numbers

### Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

## Syntax

```testtype(obj, Type::Negative)
assume(x, Type::Negative)
is(ex, Type::Negative)
```

## Description

Type::Negative represents negative numbers. Type::Negative is a property, too, which can be used in an assume call.

The call testtype(obj, Type::Negative) checks, whether obj is a negative real number and returns TRUE, if it holds, otherwise FALSE.

testtype only performs a syntactical test identifying MuPAD® objects of type DOM_INT, DOM_RAT and DOM_FLOAT and checks, if bool(obj < 0) holds. This does not include arithmetical expressions such as -exp(1), which are not identified as of type Type::Negative.

The call assume(x, Type::Negative) marks the identifier x as a negative real number.

The call is(ex, Type::Negative) derives, whether the expression ex is a negative real number (or this property can be derived).

This type represents a property that can be used in assume and is.

Instead of Type::Negative the assumption can also be assume(x < 0).

## Examples

### Example 1

The following numbers are of type Type::Negative:

```testtype(-2, Type::Negative),
testtype(-3/4, Type::Negative),
testtype(-0.123, Type::Negative),
testtype(-1, Type::Negative),
testtype(-1.02, Type::Negative)```

The following expressions are exact representations of negative numbers, but syntactically they are not of Type::Negative:

```testtype(-exp(1), Type::Negative),
testtype(-PI^2 - 5, Type::Negative),
testtype(-sin(2), Type::Negative)```

### Example 2

Assume an identifier is negative:

```assume(x, Type::Negative):
is(x, Type::Negative)```

This is equal to:

```assume(x < 0):
is(x < 0)```

Also negative numbers are real:

```assume(x, Type::Negative):
is(x, Type::Real)```

However, real numbers can be negative or not:

```assume(x, Type::Real):
is(x, Type::Negative)```

`delete x:`

## Parameters

 obj Any MuPAD object x An identifier or a mathematical expression containing identifiers ex

## Return Values

See testtype, assume and is