FORMULA_CURVE

This element creates a curve defined by a mathematical formula (y=f(x)).

Attributes brief detailed show all inherited

	Name	Description	Default
	formula	Mathematical formula for the curveThe formula can reference any other model data available (parameter, curve, surface...)	empty
	variable	name of the "x" variable in the formulaYou can customize the name of the traditional "x" variable in y=f(x) formula so that it becomes y=f(variable)	x
Events
	value_changed	the event is triggered anytime the value of the object has changed
Common attributes
	id	Identifier of the elementThe id of an element has to be globally unique. Don't start with a digit for AngelScript compatibility.	empty

	Name	Value type	Default	Description	Comment
	formula	Math Formula	empty	Mathematical formula for the curve	The formula can reference any other model data available (parameter, curve, surface...)
	variable	string	x	name of the "x" variable in the formula	You can customize the name of the traditional "x" variable in y=f(x) formula so that it becomes y=f(variable)
Events
	value_changed	event		the event is triggered anytime the value of the object has changed
Common attributes
	id	identifier	empty	Identifier of the element	The id of an element has to be globally unique. Don't start with a digit for AngelScript compatibility.

See the CURVE element attributes. The FORMULA_CURVE element does not have the persistent attribute since its value is computed automatically.

Examples

A simple FORMULA_CURVE and other elements used to display that curve on a graph nicely.

<FORMULA_CURVE id="formula_curve_demo" x_min="-50" x_max="50" x_default="0" y_default="0" y_max="1" y_min="-1" formula="sin(x)/x" />
<PNS_LCD_GROUP_BOX>
<LAYER_STACK>
<GRID id="grid_1" width="100%" height="100%" x_positions_count="11" x_subdiv_count="1" y_positions_count="3" y_subdiv_count="3" color="#CCCCCC" subdiv_color="#999999" origin_color="#FFFFFF" line_width="2" subdiv_line_width="1" origin_line_width="3" x_param_info_id="formula_curve_demo.x_info" y_param_info_id="formula_curve_demo.y_info" opacity="0.2" />
<CURVE_GRAPH curve_id="formula_curve_demo" width="500" height="200" color="#327ca3" graph_style="stroke" opacity="1" line_width="4" />
<CURVE_GRAPH curve_id="formula_curve_demo" width="500" height="200" color="#327ca3" graph_style="bargraph" opacity="0.2" line_width="4" />
<RULER id="graph_ruler_x" orientation="horizontal" width="100%" value_suffix="false" param_info_id="formula_curve_demo.x_info" color="#AAAAAA" value_format=".1" content="{value}" positions_count="11" font_escapement="0" text_h_align="center" v_offset="0" v_align="bottom" h_offset="-1" font_size="12" />
<RULER id="graph_ruler_y" orientation="vertical" height="100%" width="50" value_suffix="false" param_info_id="formula_curve_demo.y_info" color="#999999" value_format=".1" content="{value}" positions_count="3" font_escapement="0" text_v_align="top" h_align="left" text_h_align="left" h_offset="3" v_offset="0" font_size="12"/>
</LAYER_STACK>
</PNS_LCD_GROUP_BOX>

Changing variable name

Just for "cosmetic" purposes we can change the name of the variable used in the formula (instead of default "x"), so that it's maybe easier to read.

<FORMULA_CURVE id="formula_curve_demo" x_min="-50" x_max="50" x_default="0" y_default="0" y_max="1" y_min="-1" formula="sin(pos)/pos" variable="pos" />

Complex curves

You can create complex formulas for complex curves using methods like this:

<FORMULA_CURVE id="formula_curve_demo" x_min="0" x_max="7" x_default="0" y_default="0" y_max="5" y_min="-5" formula="0 + 1*(x>=1)*(x<2) + 2*(x>=2)*(x<3) + -3*(x>=3)*(x<4) + -1*(x>=5)*(x<6)" />

A smoothed curve can be achieved using tahh or similar functions.

<FORMULA_CURVE id="formula_curve_demo" x_min="0" x_max="7" x_default="0" y_default="0" y_max="5" y_min="-5" formula="0 + ((1+tanh(k*(x - 1)))/2)*(1-0) + ((1+tanh(k*(x - 2)))/2)*(2-1) + ((1+tanh(k*(x - 3)))/2)*(-3-2) + ((1+tanh(k*(x - 4)))/2)*(0--3) + ((1+tanh(k*(x - 5)))/2)*(-1+0) + ((1+tanh(k*(x - 6)))/2)*(0--1) " />
<PARAM id="k" min="2" max="30" exposed="true" default="7" />
<PARAM_TEXT_CONTROL param_id="k" />

You can take a look at this script that does similar stuff in a more complex/organized manner.

Keep in mind that drawing complex curves (and other graphics) can be done using CANVAS.

Related elements

See CURVE_GRAPH, CURVE_FROM_PARAM_OVER_TIME, GRID, RULER, CURVE, CURVE_LINK, CANVAS.

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