Intertwining [Entrelacs].
FX[x,y] = A11.PX[x,y] + A12.PY[x,y] + A13.PZ[x,y]
FY[x,y] = A21.PX[x,y] + A22.PY[x,y] + A23.PZ[x,y]
PX[x,y] = XCartesianCoordinates(PR,PP,PT)
PY[x,y] = YCartesianCoordinates(PR,PP,PT)
PZ[x,y] = ZCartesianCoordinates(PR,PP,PT)