#setup: import numpy as np ; N = 20 ; x = y = z = np.arange(0., N, 0.1) ; L = 4 ; periodic = True
#run: periodic_dist(x, x, x, L,periodic, periodic, periodic)

#pythran export periodic_dist(float [], float[], float[], int, bool, bool, bool)
import numpy as np 

def periodic_dist(x, y, z, L, periodicX, periodicY, periodicZ):
    " ""Computes distances between all particles and places the result in a matrix such that the ij th matrix entry corresponds to the distance between particle i and j"" "
    N = len(x)
    xtemp = np.tile(x,(N,1))
    dx = xtemp - xtemp.T
    ytemp = np.tile(y,(N,1))
    dy = ytemp - ytemp.T
    ztemp = np.tile(z,(N,1))
    dz = ztemp - ztemp.T

    # Particles 'feel' each other across the periodic boundaries
    if periodicX:
        dx[dx>L/2]=dx[dx > L/2]-L
        dx[dx<-L/2]=dx[dx < -L/2]+L

    if periodicY:
        dy[dy>L/2]=dy[dy>L/2]-L
        dy[dy<-L/2]=dy[dy<-L/2]+L

    if periodicZ:
        dz[dz>L/2]=dz[dz>L/2]-L
        dz[dz<-L/2]=dz[dz<-L/2]+L

    # Total Distances
    d = np.sqrt(dx**2+dy**2+dz**2)

    # Mark zero entries with negative 1 to avoid divergences
    d[d==0] = -1

    return d, dx, dy, dz