# Feedback with Rational Polynomials (Negative) (G Dataflow)

Version:

Calculates the negative feedback equation.

## p(x) numerator

Numerator coefficients, in ascending order of power, of the first rational polynomial.

This input accepts the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## p(x) denominator

Denominator coefficients, in ascending order of power, of the first rational polynomial.

This input accepts the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## q(x) numerator

Numerator coefficients, in ascending order of power, of the second rational polynomial.

This input accepts the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## q(x) denominator

Denominator coefficients, in ascending order of power, of the second rational polynomial.

This input accepts the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

## g(x) numerator

Numerator coefficients, in ascending order of power, of the negative feedback with the rational polynomial.

This output can return the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## g(x) denominator

Denominator polynomial coefficients, in ascending order of power, of the negative feedback with the rational polynomial.

This output can return the following data types:

• 1D array of double-precision, floating-point numbers
• 1D array of complex double-precision, floating-point numbers

## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

## Algorithm for Calculating the Negative Feedback with Rational Polynomials

This node uses the following equation to calculate the negative feedback:

$h\left(x\right)=\frac{p\left(x\right)}{1+p\left(x\right)q\left(x\right)}=\frac{\frac{{p}_{n}\left(x\right)}{{p}_{d}\left(x\right)}}{1+\left[\frac{{p}_{n}\left(x\right)}{{p}_{d}\left(x\right)}\right]\text{\hspace{0.17em}}\left[\frac{{q}_{n}\left(x\right)}{{q}_{d}\left(x\right)}\right]}$

where

• h(x) is the negative feedback
• p(x) is the first rational polynomial
• q(x) is the second rational polynomial
• pn(x) is the numerator polynomial of p(x)
• qn(x) is the numerator polynomial of q(x)
• pd(x) is the denominator polynomial of p(x)
• qd(x) is the denominator polynomial of q(x)

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices