id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
28072 Issue in calculus on manifolds with incomplete set of transition maps egourgoulhon "In Sage 8.8, we have
{{{
sage: M = Manifold(2, 'M')
sage: X. = M.chart()
sage: Y.__ = M.chart()
sage: X_to_Y = X.transition_map(Y, [x+y, x-y])
sage: f = M.scalar_field({X: x*y})
sage: g = M.scalar_field({Y: u*v})
sage: f + g
...
KeyError: (Chart (M, (u, v)), Chart (M, (x, y)))
}}}
If one initializes the inverse transition map, things are OK:
{{{
sage: X_to_Y.inverse()
Change of coordinates from Chart (M, (u, v)) to Chart (M, (x, y))
sage: f + g
Scalar field on the 2-dimensional differentiable manifold M
sage: _.display()
M --> R
(x, y) |--> x^2 + x*y - y^2
(u, v) |--> 1/4*u^2 + u*v - 1/4*v^2
}}}
But even without knowing the inverse transition map, Sage should be capable to compute the value of `f + g`, with the result expressed in the chart `X` only. " defect closed major sage-8.9 geometry fixed manifolds, scalar field tscrim Eric Gourgoulhon Travis Scrimshaw N/A 7d13b136fc258009992a042953ffdf3085edecf0 7d13b136fc258009992a042953ffdf3085edecf0
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