# Array-Vector Multiply

Multiply array by vector along specified dimension

## Library

Math Functions / Matrices and Linear Algebra / Matrix Operations

`dspmtrx3`

## Description

The Array-Vector Multiply block multiplies the values in the specified dimension of the N-dimensional input array A by the values in the input vector V.

The length of the input V must be the same as the length of the specified dimension of A. The Array-Vector Multiply block multiplies each element of V by the corresponding element along that dimension of A.

Consider a 3-dimensional M-by-N-by-P input array A(i,j,k) and a N-by-1 input vector V. When the Multiply along dimension parameter is set to `2`, the output of the block Y(i,j,k) is

$Y\left(i,j,k\right)=A\left(i,j,k\right)*V\left(j\right)$

where

$\begin{array}{l}1\le i\le M\\ 1\le j\le N\\ 1\le k\le P\end{array}$

The output of the Array-Vector Multiply block is the same size as the input array, A. This block accepts real and complex floating-point and fixed-point inputs.

### Fixed-Point Data Types

The following diagram shows the data types used within the Array-Vector Multiply block for fixed-point signals.

When you specify the vector V on the Main pane of the block mask, you must specify the data type and scaling properties of its elements in the Vector (V) parameter on the Data Types tab. When the vector comes in through the block port, its elements inherit their data type and scaling from the driving block.

The output of the multiplier is in the product output data type when at least one of the inputs to the multiplier is real. When both of the inputs to the multiplier are complex, the result of the multiplication is in the accumulator data type. For details on the complex multiplication performed, see Multiplication Data Types.

You can set the vector, accumulator, product output, and output data types in the block dialog as discussed below.

## Dialog Box

The Main pane of the Array-Vector Multiply block dialog appears as follows.

Multiply along dimension

Specify the dimension along which to multiply the input array A by the elements of vector V.

Vector (V) source

Specify the source of the vector, V. The vector can come from the `Input port` or from a `Dialog parameter`.

Vector (V)

Specify the vector, V. This parameter is visible only when you select `Dialog parameter` for the Vector (V) source parameter.

The Data Types pane of the Array-Vector Multiply block dialog appears as follows.

 Note:   Floating-point inheritance takes precedence over the data type settings defined on this pane. When inputs are floating point, the block ignores these settings, and all internal data types are floating point.
Rounding mode

Select the rounding mode for fixed-point operations.

Overflow mode

Select the overflow mode for fixed-point operations.

Vector (V)

Use this parameter to specify the word and fraction lengths for the elements of the vector, V. You can set this parameter to:

• A rule that inherits a data type, for example, ```Inherit: Same word length as input```

• An expression that evaluates to a valid data type, for example, `fixdt(1,16,0)`

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the Accumulator data type parameter.

 Note   The Vector (V) parameter on the Data Types pane is only visible when you select ```Dialog parameter``` for the Vector (V) source parameter on the Main pane of the block mask. When the vector comes in through the block's input port, the data type and scaling of its elements are inherited from the driving block.
Product output data type

Specify the product output data type. See Fixed-Point Data Types and Multiplication Data Types for illustrations depicting the use of the product output data type in this block. You can set it to:

• A rule that inherits a data type, for example, ```Inherit: Inherit via internal rule```

• An expression that evaluates to a valid data type, for example, `fixdt(1,16,0)`

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the Product output data type parameter.

Accumulator data type

Specify the accumulator data type. See Fixed-Point Data Types for illustrations depicting the use of the accumulator data type in this block. You can set this parameter to:

• A rule that inherits a data type, for example, ```Inherit: Inherit via internal rule```

• An expression that evaluates to a valid data type, for example, `fixdt(1,16,0)`

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the Accumulator data type parameter.

Output data type

Specify the output data type. See Fixed-Point Data Types for illustrations depicting the use of the output data type in this block. You can set it to:

• A rule that inherits a data type, for example, ```Inherit: Same as product output```

• An expression that evaluates to a valid data type, for example, `fixdt(1,16,0)`

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the Output data type parameter.

Minimum

Specify the minimum value that the block should output. The default value is `[]` (unspecified). Simulink® software uses this value to perform:

• Simulation range checking (see Signal Ranges)

• Automatic scaling of fixed-point data types

Maximum

Specify the maximum value that the block should output. The default value is `[]` (unspecified). Simulink software uses this value to perform:

• Simulation range checking (see Signal Ranges)

• Automatic scaling of fixed-point data types

Lock data type settings against changes by the fixed-point tools

Select this parameter to prevent the fixed-point tools from overriding the data types you specify on the block mask.

## Supported Data Types

PortSupported Data Types

A

• Double-precision floating point

• Single-precision floating point

• Fixed point (signed only)

• 8-, 16-, and 32-bit signed integers

V

• Double-precision floating point

• Single-precision floating point

• Fixed point (signed only)

• 8-, 16-, and 32-bit signed integers

Output

• Double-precision floating point

• Single-precision floating point

• Fixed point (signed only)

• 8-, 16-, and 32-bit signed integers