The gradient of the half-normal key function

The key function contains one parameter, the scale. Current implementation assumes that scaled dist is x/scale, not x/width

Usage

keyfct.grad.hn(distance, key.scale)

Arguments

distance

perpendicular distance vector

key.scale

vector of scale values

Value

vector of derivatives of the half-normal key function w.r.t. the scale parameter

Details

d key / d scale = exp(-y ^ 2 / (2 scale ^ 2)) * (y ^ 2 / scale ^ 3)