PS Math Function

Apply mathematical function to input physical signal

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Libraries:
Simscape / Foundation Library / Physical Signals / Functions

Description

The PS Math Function block applies a mathematical function to the value and unit of the input physical signal, u. The block output is the result of the operation of the function on the input. You can select one of the following functions from the Function choice parameter list.

Function	Description	Mathematical Expression
sin(u)	Sine	sin(u)
cos(u)	Cosine	cos(u)
exp(u)	Exponential	eu
log(u)	Natural logarithm	ln(u)
10.^u	Power of base 10	10u
log10(u)	Common (base 10) logarithm	log(u)
u.^2	Power 2	u2
sqrt(u)	Square root	u0.5
1./u	Reciprocal	1/u
tanh(u)	Hyperbolic tangent	tanh(u)
u.^v	Power	uv

The PS Math Function block issues a simulation-time error when the input falls out of the expected domain for the particular function used. For example, if set to sqrt(u), the PS Math Function block issues an error if it receives negative input during simulation.

Note

For u.^2, sqrt(u), 1./u, and u.^v the unit of the output signal is the result of the operation of the function on the input signal unit. Thus for u.^v, unless the input signal is unitless, changing the value of v changes the unit of the output signal. For all other functions in the list, the input signal must be unitless.

Examples

Nonlinear Inductor

An implementation of a nonlinear inductor where the inductance depends on the current. For best numerical efficiency, the underlying behavior is defined in terms of a current-dependent flux. In order to differentiate the flux to get voltage, a magnetizing lag is included. Simulation results are relatively insensitive to this lag provided that it is at least an order of magnitude faster than the fastest frequency of interest. Parameters for the source and lag are defined in the MATLAB® workspace so that the expected voltage can be calculated analytically.

• Open Model

Ports

Input

I — Input physical signal, u, untyped

physical signal

Input port for the operand physical signal, u.

The port name is not visible in the block icon, but you can see this name in the underlying source file by clicking the Source code link in the Description tab of the block dialog box.

Output

O — Output physical signal, untyped

physical signal

Output physical signal.

The port name is not visible in the block icon, but you can see this name in the underlying source file by clicking the Source code link in the Description tab of the block dialog box.

Parameters

Function choice — Function to perform on the operand signal

sin(u) (default) | cos(u) | exp(u) | log(u) | 10.^u | log10(u) | u.^2 | sqrt(u) | 1./u | tanh(u) | u.^v

Select the function to perform. The block output is the result of the operation of the function on the value and unit of the input signal.

v — Power

1 (default) | scalar, vector, or matrix

For the u.^v option, the value of the output signal is the value of the input signal, u, to the power of v. If v is a vector or matrix, its size must match the size of the input signal, u, or u must be a scalar.

The unit of the output signal is the result of the operation of the function on the input signal unit. Therefore, unless the input signal is unitless, changing the value of v changes the unit of the output signal.

Dependencies

To enable this parameter, set Function choice to u.^v.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2007b

R2019a: Unit Propagation

Prior to R2019a, this block did not propagate physical units.

If your model contains legacy blocks without unit propagation, use the Upgrade Advisor to upgrade your blocks to the latest version. For more information, see Upgrading Models with Legacy Physical Signal Blocks.