# Last edited on 2021-07-31 12:33:36 by jstolfi

from hann_bell import hann_bell
from basis_sample import basis_sample

def basis_2d_hann_sample(c, r, s):
  # Evluates at the sample points {s} the 2d Hann bell basis functions whose
  # centroids are in {c} and whose radii are in {r}.
  #
  # Both the centroid and radius of each basis element must be a 2-tuple of floats.
  #
  # Returns a list {B} of {nf} lists, each element being a list of
  # {ns=len(s)} floats; such that {B[i][k]} is the 2d Hann bell basis
  # element with centroid {c[i]} and radius {r[i]} evaluated at the point {s[k]}.

  nb = len(c);
  
  def basis_hann(i, p):
    # Evaluates the 2d Hann bell basis element {i} on sampling point {p}.
    
    cxi,cyi = c[i]
    rxi,ryi = r[i]
    hx = hann_bell((p[0]-cxi)/rxi)
    hy = hann_bell((p[1]-cyi)/ryi)
    Bp = hx*hy
    return Bp;
    # ......................................................................
    
  B = basis_sample(nb, basis_hann, s);
  return B
  # ----------------------------------------------------------------------