# peaks: Peaks Function (Matlab Style) In pracma: Practical Numerical Math Functions

## Description

An example functions in two variables, with peaks.

## Usage

 `1` ```peaks(v = 49, w) ```

## Arguments

 `v` vector, whose length will be used, or a natural number. `w` another vector, will be used in `meshgrid(x,y)`.

## Details

`peaks` is a function of two variables, obtained by translating and scaling Gaussian distributions, which is useful for demonstrating three-dimensional plots.

## Value

Returns three matrices as a list with `X`, `Y`, and `Z` components, the first two being the result of the `meshgrid` function, and `Z` the application of the following function at the points of `X` and `Y`:

```z <- 3 * (1-x)^2 * exp(-(x^2) - (y+1)^2) - 10 * (x/5 - x^3 - y^5) * exp(-x^2 - y^2) - 1/3 * exp(-(x+1)^2 - y^2)```

## Note

The variant that `peaks()` will display the 3-dim. graph as in Matlab is not yet implemented.

`meshgrid`

## Examples

 ```1 2 3 4 5 6 7``` ```peaks(3) ## Not run: P <- peaks() x <- P\$X[1,]; y <- P\$Y[, 1] persp(x, y, P\$Z) ## End(Not run) ```

### Example output

```\$X
[,1] [,2] [,3]
[1,]   -3    0    3
[2,]   -3    0    3
[3,]   -3    0    3

\$Y
[,1] [,2] [,3]
[1,]   -3   -3   -3
[2,]    0    0    0
[3,]    3    3    3

\$Z
[,1]       [,2]          [,3]
[1,]  6.671280e-05 -0.2449540 -5.864188e-06
[2,] -3.650620e-02  0.9810118  3.312495e-02
[3,]  3.223536e-05  0.2998710  4.102973e-05
```

pracma documentation built on Dec. 11, 2018, 3 a.m.