﻿ Euler Math Toolbox - Reference

# Interest Rates

## Content

Computes interest rates for investments.

Load these functions with "load interest".

## Interest Rates

```function rate (x:vector, n:vector=none)
```
```  Compute the interest rate in % for an investment with returns.

x : Vector of payments (negative) or income (positive) at evenly
spaced periods or at times in the vector n.
n : times of payments (default is yearly).

>load interest;
>rate([1000,-50,-50,-50,-50,-1050])+"%" // savings
5%
>rate([-1000,0,0,0,0,1200])+"%" // accumulated interest
3.71372893366%
>rate(100000|(-10150*ones(1,20))) // 20 year loan
7.95349754169
>rate([-1200,0,0,0,2100]), rate([-1200,2100],[0,4])
15.0163316896
15.0163316895

See:   simrate (Interest Rates)
```
```function simrate (v:vector, P:positive real, digits=none)
```
```  Simulates payments in vector v at rate P in %

>v=simrate(100000|(-10150*ones(1,20)),7.96,2)
[ 100000  97810  95445.68  92893.16  90137.46  87162.4  83950.53
80482.99  76739.44  72697.9  68334.65  63624.09  58538.57  53048.24
47120.88  40721.7  33813.15  26354.68  18302.51  9609.39  224.3 ]
>columnsplot(v);

```
```function map investment (start, instalment, final, n; i0=1, i1=1)
```
```  Computes the interest rate of a loan and other investments.

Note that payments are negative!

start: start investment at period 0
instalment: rate payed at the start of periods i0 to n-i1 (by
default n-1 rates)
final: that is the final dept after n periods

>print(investment(1000,-50,-1050,10),2,unit="%")
5.00%
>print(investment(1000,0,-1200,5),2,unit="%")
3.71%
>print(investment(100000,-10150,0,21),2,unit="%")
7.95%

The result is the interest rate in %.

See:   rate (Interest Rates)
```
```function finaldebt (loan,periods,rate,payment,start=1)
```
```  Compute the final dept of a loan after periods of payments.

See:   rate (Interest Rates)
```

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