Addition of the Laplacian Operator

[mohit3011]

While going through the Vector Module I noticed that Laplacian operations haven't been implemented in Sympy yet. I think this functionality can be added as in physics Laplacian operator plays a major role (like in Schrodinger Wave Equations).

Laplacian operations on Scalar functions is of importance and I would like to implement it.
What I hope after this implementation would be

>>>from sympy.vector import CoordSysCartesian, laplace
>>>R = CoordSysCartesian('R')
>>>v = R.x**2*R.y**2*R.z**2
>>>laplace(v, R)
2*R.x**2*R.y**2 + 2*R.x**2*R.z**2 + 2*R.y**2*R.z**2

[mohit3011]

@jksuom , @asmeurer , please review it. Thanks

[siefkenj]

Has this been implemented? Is it time to close this bug?

[ashu-22]

So Why we I get the issue from Triage account.I see that this issue is already revoked there.

[faze-geek]

Can be closed ,refer #12261 .