# atmosisa

Use International Standard Atmosphere model

## Syntax

``````[T,a,P,rho,nu] = atmosisa(height)``````
``[T,a,P,rho,nu] = atmosisa(height,Name=Value)``

## Description

example

``````[T,a,P,rho,nu] = atmosisa(height)``` implements the mathematical representation of the International Standard Atmosphere values for ambient temperature, `T`, pressure, `P`, speed of sound, `a`, ,density, `rho`, and kinematic viscosity, `nu`, for the input geopotential altitude, `height`, between the sea level and the tropopause. `[T,a,P,rho,nu] = atmosisa(height,Name=Value)` specifies options using one or more name-value arguments. For example, to input geopotential altitude between -5000 meters and the mesopause, set `extended` to `true`. ```

## Examples

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Calculate the International Standard Atmosphere at 1000 m.

`[T, a, P, rho] = atmosisa(1000)`
```T = 281.6500 ```
```a = 336.4341 ```
```P = 8.9875e+04 ```
```rho = 1.1116 ```

Calculate the International Standard Atmosphere at 1000, 11,000, and 20,000 m with `extended=true` to implement the mathematical representation of the International Standard Atmosphere values to between -5000 meters and the mesopause..

`[T, a, P, rho] = atmosisa([1000 11000 20000],extended=true)`
```T = 1×3 281.6500 216.6500 216.6500 ```
```a = 1×3 336.4340 295.0695 295.0695 ```
```P = 1×3 104 × 8.9875 2.2632 0.5475 ```
```rho = 1×3 1.1116 0.3639 0.0880 ```

## Input Arguments

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Geopotential heights, specified as an m-by-n array.

Data Types: `double`

### Name-Value Arguments

Specify optional pairs of arguments as `Name1=Value1,...,NameN=ValueN`, where `Name` is the argument name and `Value` is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose `Name` in quotes.

Example: `extended,false` implements the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between the sea level and the tropopause.

Mathematical representation between sea level and tropopause, specified as false or true. Set `extended` to `false` or to `'off'` to implement the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between the sea level and the tropopause.

Set `extended` to `true` or `'on'` to implement the mathematical representation of the International Standard Atmosphere values for ambient temperature, pressure, density, speed of sound, and kinematic viscosity for the input geopotential altitude between -5000 meters and the mesopause.

Function behavior when inputs are out of range, specified as one of these values.

ValueDescription
`'None'`No action.
`'Warning'`Warning in the MATLAB® Command Window and model simulation continues.
`'Error'`MATLAB returns an exception and model simulation stops.

#### Dependencies

The `atmosisa` function takes the action into account when `'extended'` is set to `'true'`.

## Output Arguments

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Temperatures, returned as an m-by-n array, in kelvin.

Speeds of sound, returned as an m-by-n array, in meters per second. The function calculates speed of sound using a perfect gas relationship.

Pressures, returned as an m-by-n array, in pascal.

Densities, returned as an m-by-n array, in kilograms per meter cubed. The function calculates density using a perfect gas relationship.

Kinematic viscosity, returned as an m-by-n array, in m2/s.

## Limitations

Set upper and lower limits for geopotential altitudes using the `'extended'` name-value argument.

• If the `'extended'` flag is set to `'false'`, the function clips the output values below the geopotential altitude of 0 meters and above the geopotential altitude of the tropopause at 20,000 meters.

• If the `'extended'` flag is set to `'true'`, the function limits the implementation to the geopotential altitude of -5000 meters (minimum) and the mesopause at 84,852 meters (maximum).

If the action input is `'error'`, an input geopotential height outside these limits results in error. If the action input is `'warning'` or `'none'`, the outputs are held at the limits.

 U.S. Standard Atmosphere, 1976. U.S. Government Printing Office, Washington, D.C.