Timeline for Error: General : {x,y} is not a valid variable
Current License: CC BY-SA 4.0
4 events
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| Sep 21, 2020 at 8:46 | history | edited | J. M.'s missing motivation♦ |
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| Aug 30, 2020 at 23:08 | comment | added | flinty |
For 2D you could try a shrinking disk using a polar substitution f[x+x0, y+y0] /. {x -> r Cos[θ], y -> r Sin[θ]} and then take the limit as r->0. If the result is dependent on θ or not a constant function then the limit is indeterminate, otherwise it should work. The same should work for a shrinking sphere in 3D. ^ Note: this assumes the f is continuous on the disks everywhere except the point x0,y0
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| Aug 30, 2020 at 22:15 | comment | added | Hausdorff |
The problem here is that Limit only gained the functionality for multi-dimensional limits in version 11.2, so in version 11 you can only consider the limit along parametrized paths. I am not sure how exactly to replace this functionality, since multi-dimensional limits are not easy to compute, as existence of the limit along a path does not prove the multi-variate limit exists (check e.g. this question)
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| Aug 30, 2020 at 21:28 | history | asked | Teo7 | CC BY-SA 4.0 |