c++ g function (INTERNAL)
gfunc_cpp(dist_mat, start, end, step, width, Lt, n, w)
A square matrix with the distances between points
A float, the start value for evaluating the g-function
A float, the last value for evaluating the g-function
A float, the jump between two evaluations of the k-function
The width of each donut
The total length of the network
The number of points
The weight of the points (coincident points)
A numeric vector with the values of the g function evaluated at the required distances