bilinear reference broken

[kongdd]

The reference of irregular bilinear interpolation is broken.
Could you give a copy of InterpolationIrregularBilinear.pdf?

http://www.ahinson.com/algorithms_general/Sections/InterpolationRegression/InterpolationIrregularBilinear.pdf

[kongdd]

In the following case, s is nan. Is that normal?

import pyresample
import numpy as np
from pyresample.bilinear._base import _get_fractional_distances_irregular

pts_irregular = (np.array([[1., 1.], ]),
                 np.array([[-1.5, 1.2], ]),
                 np.array([[-1.2, -1.4], ]),
                 np.array([[1.5, -1.3], ]))

t, s = _get_fractional_distances_irregular(pts_irregular, 0., 0.)
t, s

(array([0.49437275]), array([nan]))