# rrdelta

Compute relative pressure ratio

## Syntax

``d = rrdelta(p0,mach,g)``

## Description

example

````d = rrdelta(p0,mach,g)` computes the relative pressure ratio `d` from the static pressures `p0`, Mach numbers, `mach`, and specific heat ratios, `g`. ```

## Examples

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Determine the relative pressure ratio for three pressures.

`delta = rrdelta([101325 22632.0672 4328.1393], 0.5, 1.4)`
```delta = 1×3 1.1862 0.2650 0.0507 ```

Determine the relative pressure ratio for three pressures and three different heat ratios.

`delta = rrdelta([101325 22632.0672 4328.1393], 0.5, [1.4 1.35 1.4])`
```delta = 1×3 1.1862 0.2635 0.0507 ```

Determine the relative pressure ratio for three pressures at three different conditions.

`delta = rrdelta([101325 22632.0672 4328.1393], [0.5 1 2], [1.4 1.35 1.4])`
```delta = 1×3 1.1862 0.4161 0.3342 ```

## Input Arguments

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Static pressures, specified as a scalar or vector in pascals.

Example: `[1.4 1.35. 1.4]`

Data Types: `double`

Mach numbers, specified as a scalar or vector.

Example: `[0.5 1 2]`

Data Types: `double`

Specific heat ratios, specified as a scalar or vector.

Example: `[0.5 1 2]`

Data Types: `double`

## Output Arguments

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Relative pressure ratio, returned as a scalar or vector.

## Limitations

For cases in which total pressure ratio is desired, that is, the Mach number is nonzero, the function assumes perfect gas — with constant molecular weight, constant pressure specific heat, and constant specific heat ratio — and dry air when calculating total pressures.

## References

[1] Pratt & Whitney Aircraft. Aeronautical Vestpocket Handbook. United Technologies, August 1986.

## Version History

Introduced in R2006b