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Math Function
Perform a 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.
exp
log
10^u
log10
magnitude^2
square
sqrt
pow
conj
reciprocal
hypot
rem
mod
transpose
hermitian
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 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.
Function
|
single
|
double
|
built-in integer
|
fixed point
|
exp
|
yes
|
yes
|
--
|
--
|
log
|
yes
|
yes
|
--
|
--
|
10^u
|
yes
|
yes
|
--
|
--
|
log10
|
yes
|
yes
|
--
|
--
|
magnitude^2
|
yes
|
yes
|
yes
|
yes
|
square
|
yes
|
yes
|
yes
|
yes
|
sqrt
|
yes
|
yes
|
--
|
--
|
pow
|
yes
|
yes
|
--
|
--
|
conj
|
yes
|
yes
|
yes
|
yes
|
reciprocal
|
yes
|
yes
|
yes
|
yes
|
hypot
|
yes
|
yes
|
--
|
--
|
rem
|
yes
|
yes
|
yes
|
--
|
mod
|
yes
|
yes
|
yes
|
--
|
transpose
|
yes
|
yes
|
yes
|
yes
|
hermitian
|
yes
|
yes
|
yes
|
yes
|
All supported modes accept both real and complex inputs, except for reciprocal, which does not accept complex fixed-point inputs. 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.
- 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 data types pane of the Math Function block dialog appears as follows:
| Note
The parameters on this pane are only available when the function chosen in the Function parameter supports fixed-point data types.
|
- Output data type mode
- Set the data type and scaling of the output to be a built-in data type, the same as that of the first input, or to be inherited via an internal rule or by backpropagation. Alternatively, choose to specify the data type and scaling of the output through the Output data type and Output scaling value parameters.
- Output data type
- Set the output data type. This parameter is only visible if you select
Specify via dialog for the Output data type mode parameter.
- Output scaling value
- Set the output scaling using either binary point-only or [Slope Bias] scaling. This parameter is only visible if you select
Specify via dialog for the Output data type and scaling parameter.
- Lock output scaling so autoscaling tool can't change it
- If you select this check box, the output scaling is locked.
- Round integer calculations toward
- Select the rounding mode for fixed-point operations.
- Saturate on integer overflow
- If selected, fixed-point overflows saturate.
Characteristics
Direct Feedthrough
|
Yes
|
Sample Time
|
Specified in the Sample time parameter
|
Scalar Expansion
|
Yes, of the input when the function requires two inputs
|
Dimensionalized
|
Yes
|
Zero Crossing
|
No
|
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© 1994-2005 The MathWorks, Inc.