poly_func :
A polynomial function for xreal-typed signals.

The poly_func primitive defines a polynomial function for xreal-typed signals. With this primitive, one can define a nonlinear DC transfer function with upto three inputs.

The parameter num_in specifies the number of inputs, of which maximum value is 3. Depending on the value of this num_in parameter, the parameter array data defines the coefficients of the input-to-output polynomail equation as listed below:

1) For a single-input polynomial (num_in = 1):

out = data[0] + data[1]*in + data[2]*in^2 + data[3]*in^3 +
      data[4]*in^4 + ...

2) For a two-input polynomial (num_in = 2):

out = data[0] + data[1]*in[1] + data[2]*in[0] +
      data[3]*in[1]^2 + data[4]*in[1]*in[0] + data[5]*in[0]^2 +
      data[6]*in[1]^3 + data[7]*in[1]^2*in[0] + data[8]*in[1]*in[0]^2 + data[9]*in[0]^3 +
      data[10]*in[1]^4 + ...

3) For a three-input polynomial (num_in = 3):

out = data[0] + data[1]*in[2] + data[2]*in[1] + data[3]*in[0] +
      data[4]*in[2]^2 + data[5]*in[2]*in[1] + data[6]*in[2]*in[0] +
      data[7]*in[1]^2 + data[8]*in[1]*in[0] + data[9]*in[0]^2 +
      data[10]*in[2]^3 + data[11]*in[2]^2*in[1] + data[12]*in[2]^2*in[0] +
      data[13]*in[2]*in[1]^2 + data[14]*in[2]*in[1]*in[0] +
      data[15]*in[2]*in[0]^2 + data[16]*in[1]^3 + data[17]*in[1]^2*in[0] +
      data[18]*in[1]*in[0]^2 + data[19]*in[0]^3 +data[19]*in[2]^4 + ...

The coefficients can also be defined by a file by specifying the parameter filename. The file defines the parameter values in Python format, e.g.:

num_in = 1
data = [1.0, 2.0, 1.0]

Input/Output Terminals

Name	I/O	Type	Description
out	output	xreal	output signal
in	input	xreal	input signals

Parameters

Name	Type	Default	Unit	Description
num_in	integer	1	None	number of inputs
data	real array	‘{0.0}	None	polynomial coefficients
filename	string	“”	None	parameter definition file