Timeline for Is this result wrong because of calculation time? (and more questions about Assumptions)
Current License: CC BY-SA 3.0
9 events
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| Jun 12, 2014 at 16:24 | history | tweeted | twitter.com/#!/StackMma/status/477124384067293184 | ||
| May 14, 2013 at 21:04 | comment | added | Michael E2 |
I don't know the answer to why the assumption is forgotten, but I've observed it before. Others have asked before, but I can't find a suitable answer to refer you to (sorry!). As for the result, it looks like a Piecewise function, that is 0 in the default case (when k > 0 is false).
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| May 14, 2013 at 17:27 | history | edited | Sjoerd C. de Vries | CC BY-SA 3.0 |
added 17 characters in body
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| May 14, 2013 at 14:55 | comment | added | an offer can't refuse | Can you answer my second bold face question? And, can you tell me why mathematica can calculate 1D but not 3D, is this because computation time? | |
| May 14, 2013 at 11:57 | history | edited | Michael E2 | CC BY-SA 3.0 |
Improved formatting
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| May 14, 2013 at 11:55 | comment | added | Michael E2 | Related: mathematica.stackexchange.com/questions/19833/… | |
| May 14, 2013 at 11:54 | comment | added | Michael E2 |
FYI, in v9.0.1, I get no warning messages with UnitStep, just the correct answer. With Assumptions -> k > 0, I get a more detailed message that shows kx^2 + ky^2 + kz^2 has been factored; adding kx^2 + ky^2 + kz^2 > 0 to the assumptions removes the message, but the output is still 0. With Assuming, I get the output -(4/3) k^3 \[Pi] (-1 + UnitStep[-k]), which is cute.
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| May 14, 2013 at 11:53 | comment | added | Michael E2 | Welcome to Mma.SE! Please note that formatted code does not wrap lines. Please include returns as appropriate to make the question more readable. (Thanks!) | |
| May 14, 2013 at 7:02 | history | asked | an offer can't refuse | CC BY-SA 3.0 |