# Discrete Zero-Pole

Model system defined by zeros and poles of discrete transfer function

• Library:

• ## Description

The Discrete Zero-Pole block models a discrete system defined by the zeros, poles, and gain of a z-domain transfer function. This block assumes that the transfer function has the following form:

`$H\left(z\right)=K\frac{Z\left(z\right)}{P\left(z\right)}=K\frac{\left(z-{Z}_{1}\right)\left(z-{Z}_{2}\right)...\left(z-{Z}_{m}\right)}{\left(z-{P}_{1}\right)\left(z-{P}_{2}\right)...\left(z-{P}_{n}\right)},$`

where Z represents the zeros vector, P the poles vector, and K the gain. The number of poles must be greater than or equal to the number of zeros (n ≥ m). If the poles and zeros are complex, they must be complex conjugate pairs.

The block displays the transfer function depending on how the parameters are specified. See Zero-Pole for more information.

### Modeling a Single-Output System

For a single-output system, the input and the output of the block are scalar time-domain signals. To model this system:

1. Enter a vector for the zeros of the transfer function in the Zeros field.

2. Enter a vector for the poles of the transfer function in the Poles field.

3. Enter a 1-by-1 vector for the gain of the transfer function in the Gain field.

### Modeling a Multiple-Output System

For a multiple-output system, the block input is a scalar and the output is a vector, where each element is an output of the system. To model this system:

1. Enter a matrix of zeros in the Zeros field.

Each column of this matrix contains the zeros of a transfer function that relates the system input to one of the outputs.

2. Enter a vector for the poles common to all transfer functions of the system in the Poles field.

3. Enter a vector of gains in the Gain field.

Each element is the gain of the corresponding transfer function in Zeros.

Each element of the output vector corresponds to a column in Zeros.

## Ports

### Input

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Input signal specified as a real-valued scalar.

Data Types: `single` | `double`

### Output

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Model of system as defined by zeros, poles, and gain of discrete transfer function. The width of the output is equal to the number of columns in the Zeros matrix, or one if Zeros is a vector.

Data Types: `single` | `double`

## Parameters

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### Main

Specify the vector or matrix of zeros. The number of zeros must be less than or equal to the number of poles. If the poles and zeros are complex, they must be complex conjugate pairs.

• For a single-output system, enter a vector for the zeros of the transfer function.

• For a multiple-output system, enter a matrix. Each column of the matrix contains the zeros of a transfer function that relates the system input to one of the outputs.

#### Programmatic Use

 Block Parameter: `Zeros` Type: character vector Values: vector Default: `''`

Specify the vector of poles. The number of poles must be greater than or equal to the number of zeros. If the poles and zeros are complex, they must be complex conjugate pairs.

• For a single-output system, enter a vector for the poles of the transfer function.

• For a multiple-output system, enter a vector for the poles common to all transfer functions of the system.

#### Programmatic Use

 Block Parameter: `Poles` Type: character vector Values: vector Default: `'[0 0.5]'`

Specify vector of gain values.

• For a single-output system, enter a scalar or 1-by-1 vector for the gain of the transfer function.

• For a multiple-output system, enter a vector of gains. Each element is the gain of the corresponding transfer function in Zeros.

#### Programmatic Use

 Block Parameter: `Gain` Type: character vector Values: scalar | vector Default: `'1'`

Specify the time interval between samples. For more information, see Specifying Sample Time.

#### Programmatic Use

 Block Parameter: `SampleTime` Type: character vector Values: scalar | vector Default: `'-1'`

### State Attributes

Use this parameter to assign a unique name to the block state. The default is `' '`. When this field is blank, no name is assigned. When using this parameter, remember these considerations:

• A valid identifier starts with an alphabetic or underscore character, followed by alphanumeric or underscore characters.

• The state name applies only to the selected block.

This parameter enables State name must resolve to Simulink signal object when you click Apply.

For more information, see Apply Storage Classes to Individual Signal, State, and Parameter Data Elements (Simulink Coder).

#### Programmatic Use

 Block Parameter: `StateName` Type: character vector Values: unique name Default: `''`

Select this check box to require that the state name resolves to a Simulink® signal object.

#### Dependencies

To enable this parameter, specify a value for State name. This parameter appears only if you set the model configuration parameter Signal resolution to a value other than `None`.

Selecting this check box disables Code generation storage class.

#### Programmatic Use

 Block Parameter: `StateMustResolveToSignalObject` Type: character vector Values: `'off' | 'on'` Default: `'off'`

Choose a custom storage class package by selecting a signal object class that the target package defines. For example, to apply custom storage classes from the built-in package `mpt`, select `mpt.Signal`. Unless you use an ERT-based code generation target with Embedded Coder®, custom storage classes do not affect the generated code.

If the class that you want does not appear in the list, select `Customize class lists`. For instructions, see Target Class Does Not Appear in List of Signal Object Classes (Embedded Coder).

For information about storage classes, see Apply Storage Classes to Individual Signal, State, and Parameter Data Elements (Simulink Coder). For information about custom storage classes, see Apply Built-In and Customized Storage Classes to Data Elements (Embedded Coder).

#### Programmatic Use

 Block Parameter: `StateSignalObject` Type: character vector Values: ```'Simulink.Signal' | ''``` Default: `'Simulink.Signal'`

Select state storage class for code generation.

Use Signal object class to select custom storage classes from a package other than `Simulink`.

#### Dependencies

To enable this parameter, specify a value for State name.

#### Programmatic Use

 Block Parameter: `StateStorageClass` Type: character vector Values: ```'Auto' | 'Model default' | 'ExportedGlobal' | 'ImportedExtern' | 'ImportedExternPointer' | 'Custom' | ...``` Default: `'Auto'`

Specify a storage type qualifier such as `const` or `volatile`.

### Note

TypeQualifier will be removed in a future release. To apply storage type qualifiers to data, use custom storage classes and memory sections. Unless you use an ERT-based code generation target with Embedded Coder, custom storage classes and memory sections do not affect the generated code.

During simulation, the block uses the following values:

• The initial value of the signal object to which the state name is resolved

• Minimum and Maximum values of the signal object

#### Dependencies

To enable this parameter, set Code generation storage class to `ExportedGlobal`, `ImportedExtern`, `ImportedExternPointer`, or `Model default`. This parameter is hidden unless you previously set its value.

#### Programmatic Use

 Block Parameter: `RTWStateStorageTypeQualifier` Type: character vector Values: ```'' | 'const' | 'volatile' | ...``` Default: `''`

## Block Characteristics

 Data Types `double` | `single` Direct Feedthrough `yes` Multidimensional Signals `no` Variable-Size Signals `no` Zero-Crossing Detection `no`