Simulink®

Math Function - Perform mathematical function

Library

Math Operations

Description

The Math Function block performs numerous common mathematical functions.

You can select one of the following functions from the Function parameter list.

The block output is the result of the operation of the function on the input or inputs.

The name of the function appears on the block. Simulink software automatically draws the appropriate number of input ports.

Use the Math Function block instead of the Fcn block when you want vector or matrix output, because the Fcn block produces only scalar output.

Data Type Support

The following table shows which input data types are supported by each of the functions of the Math Function block.

All supported modes accept both real and complex inputs, except for reciprocal and sqrt, which do not accept complex fixed-point inputs. Also, sqrt does not accept fixed-point inputs that are negative or that have nontrivial slope and nonzero bias. The output signal type of the block is real or complex, depending on the setting of the Output signal type parameter.

Parameters and Dialog Box

The Main pane of the Math Function block dialog appears as follows:

Function

Specify the mathematical function. See Description for more information about the options for this parameter.

Output signal type

Select the output signal type of the Math Function block as real, complex, or auto.

	Input	Output Signal Type
Function	Signal	Auto	Real	Complex
exp, log, 10u, log10, square, sqrt, pow, reciprocal, conjugate, transpose, hermitian	real complex	real complex	real error	complex complex
magnitude squared	real complex	real real	real real	complex complex
hypot, rem, mod	real complex	real error	real error	complex error

Sample time (-1 for inherited)

Specify the time interval between samples. To inherit the sample time, set this parameter to -1. See Specifying Sample Time in the online documentation for more information.

The Signal Attributes pane of the Math Function block dialog appears as follows:

Note   Some of the parameters on this pane are available only when the function chosen in the Function parameter supports fixed-point data types.

Output minimum

Specify the minimum value that the block should output. The default value, [], is equivalent to -Inf. Simulink software uses this value to perform:

• Simulation range checking (see Checking Signal Ranges)

• Automatic scaling of fixed-point data types

Output maximum

Specify the maximum value that the block should output. The default value, [], is equivalent to Inf. Simulink software uses this value to perform:

• Simulation range checking (see Checking Signal Ranges)

• Automatic scaling of fixed-point data types

Output data type

Specify the output data type. You can set it to:

• A rule that inherits a data type, for example, Inherit: Inherit via back propagation

• The name of a built-in data type, for example, single

• The name of a data type object, for example, a Simulink.NumericType object

• An expression that evaluates to a data type, for example, float('single')

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

See Specifying Block Output Data Types for more information.

Lock output scaling against changes by the autoscaling tool

Select to lock scaling of outputs. This parameter is visible only if you enter an expression for the Output data type parameter.

Round integer calculations toward

Select the rounding mode for fixed-point operations. For more information, see Rounding in the Simulink Fixed Point User's Guide.

Saturate on integer overflow

If selected, fixed-point overflows saturate.

Characteristics

Manual Switch

MATLAB Fcn