Metric Tensor in Spherical Coordinates

samedi 28 juin 2014

I recently derived a matrix which I believe to be the metric tensor in spherical polar coordinates in 3-D. Here were the components of the tensor that I derived. I will show my work afterwards:



g11 = sin2(ø) + cos2(θ)



g12 = -rsin(θ)cos(θ)



g13 = rsin(ø)cos(ø)



g21 = -rsin(θ)cos(θ)



g22 = r2sin2(ø) + r2sin2(θ)



g23 = 0



g31 = rsin(ø)cos(ø)



g32 = 0



g33 = r2cos2(ø)



The above is what I derived, but when I tried to verify to see if my answer was correct by checking various websites, I did not see any site have what I derived.



Here is my work:



The axes were:



x1 = r



x2 = θ



x3 = ø



The vector that I differentiated was:



<rcos(θ)sin(ø) , rsin(θ)sin(ø) , rcos(θ)>



I then differentiated the vector with respect to the various axes in order to derive my tangential basis vectors.



Here were my basis vectors:



er = <cos(θ)sin(ø) , sin(θ)sin(ø), cos(θ)>



eθ = <-rsin(θ)sin(ø), rcos(θ)sin(ø) , -rsin(θ)>



eø = <rcos(θ)cos(ø), rsin(θ)cos(ø) , 0>



Finally, I did the dot product with these basis vectors to derive the components of my metric tensor.



That is how I got what I derived, but I don't see any confirmation of this online.



Can anyone please either verify if I am right with this metric tensor or tell me where I went wrong?





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