# Is a cubic Lagrange interpolation tensor product the same as bicubic interpolation?

I just implemented some interpolated texture sampling by sampling the 4x4 nearest pixels then doing Lagrange interpolation across the x axis to get four values to use Lagrange interpolation on across the y axis.

Is this the same as bicubic interpolation?

No, it turns out that it is not the same thing. Bicubic interpolation is $C1$ continuous, while lagrange is not. It's a completely different thing.