# Test problem with multiple peaks

### Description

Generates a benchmark function with multiple peaks.

### Usage

1 | ```
peaks(x)
``` |

### Arguments

`x` |
A matrix containing the values of the input variables. |

### Value

Vector of the same length as `x`

giving the values of the benchmark function.

### Author(s)

Laura Villanova, Kate Smith-Miles and Rob J Hyndman

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | ```
x1 <- seq(-3, 3, length = 50)
x2 <- x1
x<-expand.grid(x1, x2)
z <- matrix(peaks(x), nrow = length(x1))
nrz <- nrow(z)
ncz <- ncol(z)
jet.colors <- colorRampPalette( c("red", "yellow") )
nbcol <- 100
color <- jet.colors(nbcol)
zfacet <- z[-1, -1] + z[-1, -ncz] + z[-nrz, -1] + z[-nrz, -ncz]
facetcol <- cut(zfacet, nbcol)
persp(x1, x2, z, col = color[facetcol], theta = 0, phi = 10,
expand = 1, xlab = "x1", ylab = "x2", zlab = "f(x1, x2)",
ticktype = "detailed")
``` |

Want to suggest features or report bugs for rdrr.io? Use the GitHub issue tracker. Vote for new features on Trello.