This dialog is used to insert a relation in the coordinate system.
“Relation” is a common name for inequalities and equations, also known as implicit functions.
To insert a relation you use the menu item → .
To change an existing relation, you first select it in the *function list* and use → .

- Relation
Here you enter the relation you want to graph. This must either be an equation or an inequality.

and`x`

are used as the independent variables. An equation is a statement that one quantity equals another and the quantities must be separated by the = operator. For example the equation`y`

`x^2 + y^2 = 25`

will plot a circle of radius 5.An inequality is a statement that one quantity is greater or less than another, and the quantities must be separated by one of the four operators: <, >, <=, >=. An inequality can for example be

`abs(x) + abs(y) < 1`

. Two operators can be used to specify a range, for example`y < sin(x) < 0.5`

.You can use the same operators and built-in functions as for plotting graphs of functions. In addition you can also create custom functions.

- Constraints
Here you can enter optional constraints, which can be any

*numeric expression*. The relation will only be valid and plotted where the constraints are fulfilled, i.e. evaluates to a non-zero value. The constraints usually consist of a series of inequalities separated with the logical operators (`and`

,`or`

`xor`

). As for the relation,and`x`

are used as the independent variables.`y`

For example if you have the relation

`x^2 + y^2 < 25`

, which is a shaded circle, the constraints`x > 0 and y < 0`

will only show the part of the circle in the 4^{th}quadrant.- Description
Here you may enter a descriptive text to show in the

*legend*. If this field is left empty, the relation and constraints will be shown in the legend.- Properties
Here you may select a shading style for inequalities, color and width for equations. The shading

*Style*is only used for inequalities and is ignored for equations. To see overlapping inequalities they must use different styles. The*Line style*indicates the type of line drawn for equations and the border line for inequalities. The*Width*indicates the size of the line drawn for equations and the width of the border line for inequalities. For inequalities the width can be set to 0 to avoid drawing the border line.