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I have just met a problem. If say there is a triangle ijk on a manifold, D(i), D(j), D(k) are the geodesic distances from a far point to i,j,k respectively. Then g = [D(i) - D(k); D(j) - D(k)],

**what does g describe? Does is describe the gradient of the vertex k?**

If u = Vi-Vk, v = Vj-Vk where Vi, Vj, Vk are the coordinate vector in 3D, construct a matrix A = [u v], then let A = (A' * A) ^ (-1).

**Now A is a 2*2 matrix and what does A mean?**

Finally,

**let g = A * g, what's the meaning of this then?**

The context of this is in someone's programming code of computing the local gradient. Can someone help me please?

Thanks