code: def _kappaShapelets(self, shapelets, beta):
          
          output=np.zeros((len(shapelets)+1,len(shapelets)+1),'complex')
          for nl in range(0,len(shapelets)):
              for nr in range(0,len(shapelets)):
                  a_lr=shapelets[nl][nr]
                  if nl>0:
                      output[nl-1][nr+1]+=a_lr*np.sqrt(nl*(nr+1))/2
                      if nr>0:
                          output[nl-1][nr-1]+=a_lr*np.sqrt(nl*nr)/2
                  output[nl+1][nr+1]+=a_lr*np.sqrt((nl+1)*(nr+1))/2
                  if nr>0:
                      output[nl+1][nr-1]+=a_lr*np.sqrt((nl+1)*nr)/2
          return output/beta**2
docs: calculates the convergence kappa given lensing potential shapelet coefficients (laplacian/2)
          :param shapelets: set of shapelets [l=,r=,a_lr=]
          :type shapelets: array of size (n,3)
          :returns:  set of kappa shapelets.
          :raises: AttributeError, KeyError