Elements
Classes

# Element Curve

JXG.GeometryElement
↳ JXG.Curve
↳ Curve

This element is used to provide a constructor for curve, which is just a wrapper for element Curve. A curve is a mapping from R to R^2. t mapsto (x(t),y(t)). The graph is drawn for t in the interval [a,b].

The following types of curves can be plotted:

• parametric curves: t mapsto (x(t),y(t)), where x() and y() are univariate functions.
• polar curves: curves commonly written with polar equations like spirals and cardioids.
• data plots: plot line segments through a given list of coordinates.

Defined in: curve.js.
Extends JXG.Curve.

Element Summary
Constructor Attributes Constructor Name and Description

Attributes Summary
Field Attributes Field Name and Description

The curveType is set in JXG.Curve#generateTerm and used in JXG.Curve#updateCurve.

If true use a recursive bisection algorithm.

If true use the algorithm by Gillam and Hohenwarter, which was default until version 0.98.

Configure arrow head at the start position for curve.

The data points of the curve are not connected with straight lines but with bezier curves.

Configure arrow head at the end position for curve.

Number of points used for plotting triggered by up events (i.e.

Number of points used for plotting triggered by move events (i.e.

Select the version of the plot algorithm.

Apply Ramer-Douglas-Peuker smoothing.

Recursion depth used for plotting triggered by up events (i.e.

Number of points used for plotting triggered by move events in case (i.e.
Methods borrowed from class JXG.Curve:
addTransform, allocatePoints, generateTerm, getTransformationSource, hasPoint, interpolationFunctionFromArray, maxX, minX, moveTo, notifyParents, update, updateCurve, updateDataArray, updateRenderer, updateTransform, X, Y, Z
Methods borrowed from class JXG.GeometryElement:
_set, addChild, addDescendants, addParents, addParentsFromJCFunctions, addRotation, addTicks, animate, bounds, clearTrace, cloneToBackground, countChildren, createGradient, createLabel, draggable, fullUpdate, generatePolynomial, getAttribute, getAttributes, getLabelAnchor, getName, getParents, getProperty, getSnapSizes, getTextAnchor, getType, handleSnapToGrid, hide, hideElement, labelColor, noHighlight, normalize, prepareUpdate, remove, removeAllTicks, removeChild, removeDescendants, removeTicks, resolveShortcuts, setArrow, setAttribute, setDash, setDisplayRendNode, setLabel, setLabelText, setName, setParents, setPosition, setPositionDirectly, setProperty, show, showElement, snapToPoints, updateVisibility
Events borrowed from class JXG.GeometryElement:
attribute, attribute:key, down, drag, keydrag, mousedown, mousedrag, mousemove, mouseout, mouseover, mouseup, move, out, over, pendown, pendrag, penup, touchdown, touchdrag, touchup, up
Element Detail
Curve
This element has no direct constructor. To create an instance of this element you have to call JXG.Board#create with type "curve".

Possible parent array combinations are:
{function|number} x
{function|number} y
{function|number} a   Optional
{function|number} b   Optional

Parent elements for Parametric Curves.

x describes the x-coordinate of the curve. It may be a function term in one variable, e.g. x(t). In case of x being of type number, x(t) is set to a constant function. this function at the values of the array.

y describes the y-coordinate of the curve. In case of a number, y(t) is set to the constant function returning this number.

Further parameters are an optional number or function for the left interval border a, and an optional number or function for the right interval border b.

Default values are a=-10 and b=10.

{array} x
{array|function|number} y

Parent elements for Data Plots.

x and y are arrays contining the x and y coordinates of the data points which are connected by line segments. The individual entries of x and y may also be functions. In case of x being an array the curve type is data plot, regardless of the second parameter and if additionally the second parameter y is a function term the data plot evaluates.

{function} r
{array|function|number} offset   Optional
{function|number} a   Optional
{function|number} b   Optional

Parent elements for Polar Curves.

The first parameter is a function term r(phi) describing the polar curve.

The second parameter is the offset of the curve. It has to be an array containing numbers or functions describing the offset. Default value is the origin [0,0].

Further parameters are an optional number or function for the left interval border a, and an optional number or function for the right interval border b.

Default values are a=-10 and b=10.

Additionally, a curve can be created by providing a curve and a transformation (or an array of transformations). The result is a curve which is the transformation of the supplied curve.

See:
JXG.Curve
Examples:
```// Parametric curve
// Create a curve of the form (t-sin(t), 1-cos(t), i.e.
// the cycloid curve.
var graph = board.create('curve',
[function(t){ return t-Math.sin(t);},
function(t){ return 1-Math.cos(t);},
0, 2*Math.PI]
);
```

```// Data plots
// Connect a set of points given by coordinates with dashed line segments.
// The x- and y-coordinates of the points are given in two separate
// arrays.
var x = [0,1,2,3,4,5,6,7,8,9];
var y = [9.2,1.3,7.2,-1.2,4.0,5.3,0.2,6.5,1.1,0.0];
var graph = board.create('curve', [x,y], {dash:2});
```

```// Polar plot
// Create a curve with the equation r(phi)= a*(1+phi), i.e.
// a cardioid.
var a = board.create('slider',[[0,2],[2,2],[0,1,2]]);
var graph = board.create('curve',
[function(phi){ return a.Value()*(1-Math.cos(phi));},
[1,0],
0, 2*Math.PI],
{curveType: 'polar'}
);
```

``` // Draggable Bezier curve
var col, p, c;
col = 'blue';
p = [];
p.push(board.create('point',[-2, -1 ], {size: 5, strokeColor:col, fillColor:col}));
p.push(board.create('point',[1, 2.5 ], {size: 5, strokeColor:col, fillColor:col}));
p.push(board.create('point',[-1, -2.5 ], {size: 5, strokeColor:col, fillColor:col}));
p.push(board.create('point',[2, -2], {size: 5, strokeColor:col, fillColor:col}));

c = board.create('curve', JXG.Math.Numerics.bezier(p),
{strokeColor:'red', name:"curve", strokeWidth:5, fixed: false}); // Draggable curve
```

```        // The curve cu2 is the reflection of cu1 against line li
var li = board.create('line', [1,1,1], {strokeColor: '#aaaaaa'});
var reflect = board.create('transform', [li], {type: 'reflect'});
var cu1 = board.create('curve', [[-1, -1, -0.5, -1, -1, -0.5], [-3, -2, -2, -2, -2.5, -2.5]]);
var cu2 = board.create('curve', [cu1, reflect], {strokeColor: 'red'});

```

Attribute Detail
{String} curveType
The curveType is set in JXG.Curve#generateTerm and used in JXG.Curve#updateCurve. Possible values are
• 'none'
• 'plot': Data plot
• 'parameter': we can not distinguish function graphs and parameter curves
• 'functiongraph': function graph
• 'polar'
• 'implicit' (not yet)
Only parameter and plot are set directly. Polar is set with JXG.GeometryElement#setAttribute only.
Defined in: options.js.
Default Value:
null

If true use a recursive bisection algorithm. It is slower, but usually the result is better. It tries to detect jumps and singularities.
Defined in: options.js.
Default Value:
true

If true use the algorithm by Gillam and Hohenwarter, which was default until version 0.98.
Defined in: options.js.
See:
Default Value:
false

{Boolean / Object} firstArrow
Configure arrow head at the start position for curve. Recommended arrow head type is 7.
Defined in: options.js.
See:
Line#firstArrow for options
Default Value:
false

{Boolean} handDrawing
The data points of the curve are not connected with straight lines but with bezier curves.
Defined in: options.js.
Default Value:
false

{Boolean / Object} lastArrow
Configure arrow head at the end position for curve. Recommended arrow head type is 7.
Defined in: options.js.
See:
Line#lastArrow for options
Default Value:
false

{Number} numberPointsHigh
Number of points used for plotting triggered by up events (i.e. high quality plotting) in case Curve#doAdvancedPlot is false.
Defined in: options.js.
See:
Default Value:
1600

{Number} numberPointsLow
Number of points used for plotting triggered by move events (i.e. lower quality plotting but fast) in case Curve#doAdvancedPlot is false.
Defined in: options.js.
See:
Default Value:
400

{Number} plotVersion
Select the version of the plot algorithm.
• Version 1 is very outdated
• Version 2 is the default version in JSXGraph v0.99.*, v1.0, and v1.1, v1.2.0
• Version 3 is an internal version that was never published in a stable version.
• Version 4 is available since JSXGraph v1.2.0
Version 4 plots correctly logarithms if the function term is supplied as string (i.e. as JessieCode)
Defined in: options.js.
`  var c = board.create('functiongraph', ["log(x)"]);`
Default Value:
2

{Boolean} RDPsmoothing
Apply Ramer-Douglas-Peuker smoothing.
Defined in: options.js.
Default Value:
false

{Number} recursionDepthHigh
Recursion depth used for plotting triggered by up events (i.e. high quality plotting) in case Curve#doAdvancedPlot is true.
Defined in: options.js.
See:
Default Value:
17

{Number} recursionDepthLow
Number of points used for plotting triggered by move events in case (i.e. lower quality plotting but fast) Curve#doAdvancedPlot is true.
Defined in: options.js.
See:
Default Value:
13

Attributes borrowed from other Elements
Attributes borrowed from class JXG.GeometryElement:

Fields borrowed from other Elements
Fields borrowed from class JXG.Curve:
dataX, dataY, numberPoints, qdt, ticks
Fields borrowed from class JXG.GeometryElement:
_org_type, _pos, ancestors, baseElement, board, childElements, descendants, dump, elementClass, elType, hasLabel, highlighted, id, inherits, isDraggable, isReal, lastDragTime, methodMap, mouseover, name, needsUpdate, notExistingParents, numTraces, parents, quadraticform, rendNode, stdform, subs, symbolic, traces, transformations, type, visProp, visPropCalc

Methods borrowed from other Elements
Methods borrowed from class JXG.Curve:
addTransform, allocatePoints, generateTerm, getTransformationSource, hasPoint, interpolationFunctionFromArray, maxX, minX, moveTo, notifyParents, update, updateCurve, updateDataArray, updateRenderer, updateTransform, X, Y, Z
Methods borrowed from class JXG.GeometryElement:
_set, addChild, addDescendants, addParents, addParentsFromJCFunctions, addRotation, addTicks, animate, bounds, clearTrace, cloneToBackground, countChildren, createGradient, createLabel, draggable, fullUpdate, generatePolynomial, getAttribute, getAttributes, getLabelAnchor, getName, getParents, getProperty, getSnapSizes, getTextAnchor, getType, handleSnapToGrid, hide, hideElement, labelColor, noHighlight, normalize, prepareUpdate, remove, removeAllTicks, removeChild, removeDescendants, removeTicks, resolveShortcuts, setArrow, setAttribute, setDash, setDisplayRendNode, setLabel, setLabelText, setName, setParents, setPosition, setPositionDirectly, setProperty, show, showElement, snapToPoints, updateVisibility

Events borrowed from other Elements
Events borrowed from class JXG.GeometryElement:
attribute, attribute:key, down, drag, keydrag, mousedown, mousedrag, mousemove, mouseout, mouseover, mouseup, move, out, over, pendown, pendrag, penup, touchdown, touchdrag, touchup, up
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