Select the third option of waveform definition and then choose the '''Custom''' option from the '''Waveform Type''' dropdown list. Enter a mathematical expression for your custom waveform a function of the time variable "T" or "t" in the box labeled '''Expression'''. You can use arithmetic operation, standard and library functions as well as you models and variables. For example, in the figure on the right, we have defined a modulated Bessel waveform in the form of "sin(2*pi*Fc*T-pi/4)*Jn(0,pi*Fc*T/4)", where Fc is the center frequency of the project and one of the project's default variables and Jn(n,x) denotes the Bessel function of the first kind and order n, which is one of [[EM.Cube]]'s library functions.
[[Image:Info_icon.png|40px]] Click here to see a '''[[List of Library Functions]]'''. [[Image:Info_icon.png|40px]] Click here to learn more about '''[[Parametric_ModelingUsing Python to Create Functions,_Sweep_%26_OptimizationModels & Scripts#Creating_Custom_Functions_Using_Models Creating Custom Python Functions | Creating Custom Python Functions Using Models]]'''.
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