Peaks Function (Matlab Style)

An example functions in two variables, with peaks.

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.

See also

meshgrid

Examples

peaks(3)
#> $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
#> 
#> $Z
#>               [,1]       [,2]          [,3]
#> [1,]  6.671280e-05 -0.2449540 -5.864188e-06
#> [2,] -3.650620e-02  0.9810118  3.312495e-02
#> [3,]  3.223536e-05  0.2998710  4.102973e-05
#> 
if (FALSE) { # \dontrun{
P <- peaks()
x <- P$X[1,]; y <- P$Y[, 1]
persp(x, y, P$Z)
} # }