id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
27856,Tangent vectors should act as derivations on scalar fields,Eric Gourgoulhon,,"In Sage 8.7, we have
{{{
sage: M = Manifold(2, 'M')
sage: X. = M.chart()
sage: p = M((2,-1), name='p')
sage: TpM = M.tangent_space(p)
sage: v = TpM((-2, 3), name='v'); v
Tangent vector v at Point p on the 2-dimensional differentiable manifold M
sage: f = M.scalar_field(x*y^2, name='f')
sage: v(f)
Traceback (most recent call last):
...
TypeError: the argument no. 1 must be a linear form
}}}
Note that this works for vector ''fields'':
{{{
sage: w = M.vector_field(name='w')
sage: w[:] = -y, x
sage: w.display()
w = -y d/dx + x d/dy
sage: w(f)
Scalar field w(f) on the 2-dimensional differentiable manifold M
sage: w(f).display()
w(f): M --> R
(x, y) |--> 2*x^2*y - y^3
}}}
This issue has been reported in this [https://ask.sagemath.org/question/46593/tangent-space-vector-mapping/ ask.sagemath question].",defect,closed,major,sage-8.8,geometry,fixed,"vector, derivation",Travis Scrimshaw,,Eric Gourgoulhon,Travis Scrimshaw,N/A,,4c0abd75065fae7820988a6eb8c2a0ebcb3091f9,4c0abd75065fae7820988a6eb8c2a0ebcb3091f9,,