# Sage manifold error

HI, there. I tried to compute some examples with Sage manifolds and I got this:

## sage: E2 = Manifold(2, 'E^2', latex_name=r'\mathbb{E}^2',start_index=1)

NotImplementedError Traceback (most recent call last) <ipython-input-37-4b1cf0743b4e> in <module>() ----> 1 E2 = Manifold(Integer(2), 'E^2', latex_name=r'\mathbb{E}^2',start_index=Integer(1))

/usr/lib/sagemath/src/sage/misc/lazy_import.pyx in sage.misc.lazy_import.LazyImport.__call__ (/usr/lib/sagemath//src/build/cythonized/sage/misc/lazy_import.c:3627)() 384 True 385 """ --> 386 return self._get_object()(args, *kwds) 387 388 def __repr__(self):

/usr/lib/sagemath/local/lib/python2.7/site-packages/sage/manifolds/manifold.py in Manifold(dim, name, latex_name, field, structure, start_index, **extra_kwds) 1653 else: 1654 raise NotImplementedError("manifolds of type {} are not ".format(structure) + -> 1655 "implemented") 1656 return TopologicalManifold(dim, name, field, structure, 1657 latex_name=latex_name, start_index=start_index,

NotImplementedError: manifolds of type smooth are not implemented

How could I fix it?

PS: My plan is to compute metric, connection, curvature, and riemann tensors. PS(II): Are differential forms implemented in Sage? Thanks!

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That's because you are using the part of SageManifolds that is implemented in SageMath 7.2. This part is very limited and does not include smooth manifolds yet. Indeed SageManifolds is being gradually incorporated in SageMath (see https://trac.sagemath.org/ticket/18528). Hopefully smooth manifolds should appear in SageMath 7.3.

Meanwhile, the solution is to install the full SageManifolds atop SageMath 7.2, following these instructions.

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