physconst

Physical constants

Syntax

Const = physconst(Name)


Description

Const = physconst(Name) returns the constant specified in the Name argument. Valid values are 'LightSpeed', 'Boltzmann', or 'EarthRadius'. Values are in SI units.

Input Arguments

Name	Character vector that indicates which physical constant the function returns. Values are not case sensitive.

Output Arguments

Const

Value of physical constant specified in the input argument Name.

Examples

Convert Frequency to Wavelength

Determine the wavelength of a 1 GHz electromagnetic wave.

freq = 1e9;
lambda = physconst('LightSpeed')/freq

lambda = 0.2998

Thermal Noise Power

Approximate the thermal noise power per unit bandwidth in the I and Q channels of a receiver.

Specify the receiver temperature and Boltzmann constant.

T = 290;
k = physconst('Boltzmann');

Compute the noise power per unit bandwidth, split evenly between the in-phase and quadrature channels.

Noise_power = 10*log10(k*T/2);

More About

Physical Constants

This table lists the supported constants and their values in SI units.

Constant	Description	Value
'LightSpeed'	Speed of light in vacuum	299,792,458 m/s. Most commonly denoted by c.
'Boltzmann'	Boltzmann constant relating energy to temperature	$$1.38\times {10}^{-23}$$ J/K. Most commonly denoted by k.
'EarthRadius'	Mean radius of the Earth	6,371,000 m

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

Does not support variable-size inputs.

Introduced in R2011a

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