DSP Blockset

Polynomial Evaluation

Evaluate a polynomial expression.

Library

Math Functions / Polynomial Functions

Description

The Polynomial Evaluation block applies a polynomial function to the real or complex input at the In port.

• y = polyval(u)           % Equivalent MATLAB code
  

The Polynomial Evaluation block performs these types of operation more efficiently than the equivalent construction using Simulink Sum and Math Function blocks.

When the Use constant coefficients check box is selected, the polynomial expression is specified by the Constant coefficients parameter. When Use constant coefficients is not selected, a variable polynomial expression is specified by the input to the Coeffs port. In both cases, the polynomial is specified as a vector of real or complex coefficients in order of descending exponents.

The table below shows some examples of the block's operation for various coefficient vectors.

Coefficient Vector	Equivalent Polynomial Expression
[1 2 3 4 5]
[1 0 3 0 5]
[1 2+i 3 4-3i 5i]

Each element of a vector or matrix input to the In port is processed independently, and the output size and frame status are the same as the input.

Dialog Box

Use constant coefficients

When selected, enables the Constant coefficients parameter and disables the Coeffs input port.

Constant coefficients

The vector of polynomial coefficients to apply to the input, in order of descending exponents. This parameter is enabled when the Use constant coefficients check box is selected.

Supported Data Types

• Double-precision floating point
• Single-precision floating point

To learn how to convert to the above data types in MATLAB and Simulink, see Supported Data Types and How to Convert to Them.

See Also

Least Squares Polynomial Fit	DSP Blockset
Math Function	Simulink
Sum	Simulink
polyval	MATLAB

Also see Polynomial Functions for a list of all the blocks in the Polynomial Functions library.

Permute Matrix

Polynomial Stability Test