#### IfcVector

Natural language names

##### Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: The vector is defined in terms of the direction and magnitude of the vector. The value of the magnitude attribute defines the magnitude of the vector.

> NOTE: The magnitude of the vector can not be reliable calculated from the components of the Orientation attribute. This form of representation was selected to reduce problems with numerical instability. For example a vector of magnitude 2.0 mm and equally inclined to the coordinate axes could be represented with Orientation attribute of (1.0,1.0,1.0).

> NOTE: Corresponding STEP entity: vector. Please refer to ISO/IS 10303-42:1994, p.27 for the final definition of the formal standard. The derived attribute Dim has been added (see also note at IfcGeometricRepresentationItem).

> HISTORY: New entity in IFC Release 1.0

Attribute definitions

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
1 | Orientation | IfcDirection | [1:1] | The direction of the vector. | X
2 | Magnitude | IfcLengthMeasure | [1:1] | The magnitude of the vector. All vectors of Magnitude 0.0 are regarded as equal in value regardless of the orientation attribute. | X
| Dim :=Orientation.Dim | IfcDimensionCount | [1:1] | The space dimensionality of this class, it is derived from Orientation | X

Formal Propositions

Rule | Description
--- | ---
WR1 | The magnitude shall be positive or zero.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | A
--- | --- | --- | --- | --- | ---
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcVector
1 | Orientation | IfcDirection | [1:1] | The direction of the vector. | X
2 | Magnitude | IfcLengthMeasure | [1:1] | The magnitude of the vector. All vectors of Magnitude 0.0 are regarded as equal in value regardless of the orientation attribute. | X
| Dim :=Orientation.Dim | IfcDimensionCount | [1:1] | The space dimensionality of this class, it is derived from Orientation | X

##### Formal representations

XSD Specification
`<xs:element name="IfcVector" type="ifc:IfcVector" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcVector">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem">
<xs:sequence>
<xs:element name="Orientation" type="ifc:IfcDirection" nillable="true"/>
</xs:sequence>
<xs:attribute name="Magnitude" type="ifc:IfcLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcVector
SUBTYPE OF (IfcGeometricRepresentationItem);
Orientation : IfcDirection;
Magnitude : IfcLengthMeasure;
DERIVE
Dim : IfcDimensionCount := Orientation.Dim;
WHERE
WR1 : Magnitude >= 0.0;
END_ENTITY;

EXPRESS-G diagram

`

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