# Powell: Powell's method for finding a functions local minimum. In BarBorGradient: Function Minimum Approximator

## Description

Powell's method for finding a function local minimum. The function need not be differentiable, and no derivatives are taken. The function must be a real-valued function of a fixed number of real-valued inputs.

## Usage

 `1` ```Powell(exp,eps,G,eta,m,k,x,v,n) ```

## Arguments

 `exp` Expression of the function to be minimized. `eps` Precision of the approximation, recommended value is 10^-10. `G` Inner approximation coefficient, recommended value is 10^-2. `eta` Inner approximation coefficient, recommended value is G*2. `m` Inner steps, recommended value is 20. `k` Second inner approximation steps, recommended value is 20. `x` Starting point of the approximation. `v` A character vector of the functions variables. Exmaple: the two dimension fuction x1*x1+10*x2*x2 needs a c("x1","x2") vector. `n` Maximum setps to make while approximating, if the calculation reaches this number it exits with the current value and point. Recommended to be 10000.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```test1 = expression(100*(x1*x1-x2)*(x1*x1-x2)+(1-x1)*(1-x1)) eps = 10^-5 G = 10^-2 eta = G *2 m = 20 k = 20 n = 10000 max = 1000 x = c(1,1) v = c("x1","x2") Powell(test1,eps,G,eta,m,k,x,v,n) ```

### Example output

```[1] "Stacionarius pont: "
[1] 1 1
[1] "Fuggveny ertek: "
[1] 0
[1] "Lepesszam: "
[1] 1
```

BarBorGradient documentation built on May 29, 2017, 7:21 p.m.