Expression

Type:string Range:[] Default:-/- Appearance:simple Excludes:Function, Module

This parameter is used to define the height profile of the texture by means of a Python expression within the layout.jcm input file. For example, the following declarations defines a Gaussian bump:

Texture {
  Python {
    Expression = "value=40*exp(-3e-3*X[0]*X[0]-3e-3*X[1]*X[1])"
  }

In general the syntax is as follows:

Python {
   Expression = " ... # your python scripting
                  ...
                  value = ... # set return value

                 "

   # define one or more parameters
   Parameter {
     Name = "Para1"
     ...
   }
   Parameter {
     Name = "Para2"
     ...

   }
}

The string value Expression has to be valid Python code and is interpreted in the following way:

• The NumPy-package is automatically imported when evaluating the expression.
• Any parameter as defined by a Parameter section is available within the Python expression as an NumPy object named accordingly to the value of the parameter Name.
• The position is available as a NumPy object with name x.
• The expression must define a scalar value which contains -elongation of the height profile.
• Keep in mind the Python indentation rule.