# wavelen2freq

Convert wavelength to frequency

## Syntax

``freq = wavelen2freq(wavelen)``
``freq = wavelen2freq(wavelen,c)``
``[freq,c] = wavelen2freq(___)``

## Description

example

````freq = wavelen2freq(wavelen)` converts wavelength `wavelen` to frequency `freq` using the speed of light in vacuum.```

example

````freq = wavelen2freq(wavelen,c)` also specifies the signal propagation speed `c`.```

example

````[freq,c] = wavelen2freq(___)` also returns the propagation speed `c` used to compute frequency `freq`. Use this syntax with any of the input arguments in previous syntaxes.```

## Examples

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Calculate the frequencies corresponding to wavelengths of 1 and 4 cm. Use the default speed of propagation.

```wavelen = [1e-2,4e-2]; freq = wavelen2freq(wavelen)```
```freq = 1×2 1010 × 2.9979 0.7495 ```

Calculate the frequency corresponding to a wavelength of 2 cm. Obtain the propagation speed used to compute the frequency.

```wavelen = 0.02; [freq,c] = wavelen2freq(wavelen,3.0e8)```
```freq = 1.5000e+10 ```
```c = 300000000 ```

## Input Arguments

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Signal wavelength, specified as a positive scalar or length-M vector of positive values. Units are in meters.

Signal propagation speed, specified as a positive scalar. The default value is obtained from `physconst('Lightspeed')`. Units are in m/s.

Example: 3.0e8

Data Types: `double`

## Output Arguments

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Signal frequency, specified as a positive scalar or a length-M vector of positive values. The size of `freq` equals the size of `wavelen`. Units are in Hz.

Example: `10e6`

Data Types: `double`

Signal propagation speed, returned as a positive scalar. Units are in m/s.

Data Types: `double`

## Version History

Introduced in R2021a