# psaspeed2rate

Single monthly mortality rate given PSA speed

## Syntax

``[CPRPSA,SMMPSA] = psaspeed2rate(PSASpeed)``

## Description

example

````[CPRPSA,SMMPSA] = psaspeed2rate(PSASpeed)` calculates vectors of PSA prepayments, each containing 360 prepayment elements, to represent the 360 months in a 30-year mortgage pool.```

## Examples

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This example shows how to compute the prepayment and mortality rates, given a mortgage-backed security with annual speed set at the PSA default benchmark.

```PSASpeed = [100 200]; [CPRPSA, SMMPSA]= psaspeed2rate(PSASpeed)```
```CPRPSA = 360×2 0.0020 0.0040 0.0040 0.0080 0.0060 0.0120 0.0080 0.0160 0.0100 0.0200 0.0120 0.0240 0.0140 0.0280 0.0160 0.0320 0.0180 0.0360 0.0200 0.0400 ⋮ ```
```SMMPSA = 360×2 0.0002 0.0003 0.0003 0.0007 0.0005 0.0010 0.0007 0.0013 0.0008 0.0017 0.0010 0.0020 0.0012 0.0024 0.0013 0.0027 0.0015 0.0031 0.0017 0.0034 ⋮ ```
```% view the plot of the output psaspeed2rate(PSASpeed)```

## Input Arguments

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Annual speed relative to the benchmark, specified as any value > `0` using an `NSPD`-by-`1` vector. The PSA benchmark is `100`.

Data Types: `double`

## Output Arguments

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PSA conditional prepayment rate, returned as a `360`-by-`NSPD` vector in decimals.

PSA monthly default rate, returned as a `360`-by-`NSPD` vector in decimals.

## References

[1] PSA Uniform Practices, SF-49