ArbitraryCurve()

The ArbitraryCurve() function allows you to generate a curve from an arbitrary mathematical expression of node-voltage and branch-current waveforms. Additionally, the arbitrary mathematical expression can include built-in vector functions, which are all described in Function Reference.

The syntax of the ArbitraryCurve() function has the following syntax with the arguments explained in the table below:

ArbitraryCurve(vector_expression, vectors_to_keep, curve_name, graph_name, grid_index, axis_name, OPTIONAL_PARAMETER_STRING)

*   For additional information about graph_name, grid_index, and axis_name, see Graph Address System.

Optional Parameters

The following syntax rules apply to the OPTIONAL_PARAMETER_STRING  argument:

• The OPTIONAL_PARAMETER_STRING  value must not contain a comma.
• The OPTIONAL_PARAMETER_STRING  is parsed on the equal sign.
• Since the argument is parsed on the equal sign, the value itself must not contain an equal sign. For example, the following is an invalid entry:
  ylabel=Body Diode Forward Current Temp=-40
  In this case , the program would read this incorrectly as two optional parameters:

• ylabel=Body Diode Forward Current

• Temp=-40

Spaces in values are allowed as long as no spaces are on either side of the equal sign. Thee three examples below illustrate this:

• ylabel=Body Diode Forward Current: valid entry with no spaces around the equal sign
• ylabel =Body Diode Forward Current: invalid entry with space before equal sign
• ylabel= Body Diode Forward Current:  invalid entry with space after equal sign

The following table lists the available formatting options for use in the OPTIONAL_PARAMETER_STRING argument.

Specifying a Color

You have three options for specifying the color for a curve:

• Color-name Alias
• Hexadecimal Color
• SIMetrix Sequence

Color-name Alias

The syntax for the color-name alias is as follows:
color=color_name
where color_name is one of the 16 built-in color aliases as listed in the following table with the hexadecimal code.

Hexadecimal Color

The syntax for the hexidecimal color is as follows:
color=#rrggbb
where rr, gg, and bb are hex numbers from 00 to FF.

You can specify any color for the curve by using a hexadecimal specification.

SIMetrix Sequence

The syntax for the SIMetrix sequence method of specifying a color is as follows:
color=SEQ:n
where n is a positive integer between 1 and 20.

SIMetrix has eight default curve colors, starting with red, green, blue, etc.

To change and extend these colors to a maximum of 20 user-defined curve colors, follow these steps:

1. From the command shell menu, select File ▶Options ▶Colour....
2. Double click a curve item in the list and then select another color from the palette, and click OK.

Note: If you do not set each Curve item in the list, the sequence wraps; for example, with the default curve colors, SEQ:9 yields the same curve color as SEQ:1.

Note: The array argument is bounded by open and close brackets [ ], and the string elements in the array are each enclosed in single quotes.

• The return value from this function is a real value with 0 indicating success and 1 indicating an error.
• Error messages are displayed in the command shell for each function call.

Note: Using the script function in a post or final process script produces slightly different results than calling this function from a testplan. The post-process script does not set the vectors_to_keep argument because this would need to be performed before the simulation run executes. The simplest way to keep the necessary vectors during a simulation run is to place a voltage probe on the required schematic node and uncheck each Analysis checkbox in the edit dialog. This probe would then keep the voltage or current to which it is attached but would not create a curve.