meta user
network profile
| bio | website | |
|---|---|---|
| location | China | |
| age | ||
| visits | member for | 9 months |
| seen | 8 hours ago | |
| stats | profile views | 134 |
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Sep 30 |
comment |
how to read in a file in the same directory? @stevenvh What?! I didn't know that! |
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Sep 22 |
accepted | ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables @celtschk That's all because that we already have a MachinePrecision in this talk, and, I think, to have two comments won't be a bad thing, since I can give you two upvote then XD. |
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Sep 20 |
comment |
For[] or While[] can't be used inside Manipulate[]? @AlbertRetey ? You mean that the date isn't tracked in any case in your last comment? Then how to explain the behaviour of Object 4 and Object 5? Also, I observed the case that the endless loop won't appear if Object 4 and Object 5 are not shown up in the notebook concurrently, I mean we should drag the scrollbar and let at least part of the Object be seen, or the loop won't happen, is this what you found? |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables @celtschk So we can simply regard MachinePrecision as something difficult to handle and always avoid it and choose a exact precision or rationalize the number will be better when having numeric calculation? By the way, it really took me a while to notice M. is for mathematica :D. |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables If so, well, it's a little different from my imagination, since I think the approximation will only be done in the last step and the precision before the last step will be as high as possible (in my mind it almost equals to infinity…), just like what I turn to do when calculating something manually…and now I notice that my imagination is unreasonable. |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables I've read the answer and the links given by J.M and @Mr.Wizard. Let me try to retell it to see if I've understand it: The error occurs because when doing numeric calculations Mma will keep the precision step by step i.e. several steps of approximation have been done before the final result comes out. |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables @celtschk So a simpler example can be, 1.00+0.00100 is calculated to 3 digits, then the answer is 1.00, right? If so, OK…I know this, though my lesson say little about numeric error analysis it's still involved in the little, but I don't expect it also exists in mathematica 囧. |
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Sep 20 |
comment |
ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables @whuber Merge? You mean shape two as one? It is possible? That would be good! I have no objection. |
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Sep 19 |
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ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables @halirutan Haha, never mind, and in fact I really don't have numerical error analysis in my university…at least it's not a required course for my major and in my memory I never see this in the list of elective course, too… our lessons always talk about those analytical solutions and say little about numeric solutions, usually the books just say "the numeric solution should be done with computer". So, can you explain the details? |
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Sep 19 |
awarded | Talkative |
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Sep 19 |
asked | ReplaceAll[] and Limit[] don't give correct results for this expression under extreme variables |
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Sep 19 |
comment |
For[] or While[] can't be used inside Manipulate[]? Albert found the truth for While…see my edit for the question for more details. |
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Sep 19 |
revised |
For[] or While[] can't be used inside Manipulate[]? added 649 characters in body |
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Sep 19 |
accepted | For[] or While[] can't be used inside Manipulate[]? |
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Sep 19 |
comment |
For[] or While[] can't be used inside Manipulate[]? @AlbertRetey ……You get the truth, I've added the conclusion to the question. OK, this time question is completely solved :D. |
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Sep 18 |
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For[] or While[] can't be used inside Manipulate[]? Hehe, yeah, that's a good resource, and as I said in the comment below, this question is more for curiosity :D, and, I've added the most puzzled code to my question: that's indeed a sample that can't be solved without adding both i and date as the local symbols. |
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Sep 18 |
revised |
For[] or While[] can't be used inside Manipulate[]? added 216 characters in body |
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Sep 18 |
comment |
For[] or While[] can't be used inside Manipulate[]? @AlbertRetey Oh, I should have add the sample…in fact my i=1 is set in the expressions:Manipulate[Module[{j}, date = Table[0, {num}]; j = 1;
While[j <= num, date[[j]] = Sin[j]; j++];
ListPlot[{date}]], {{num, 2}, 1, 20, 1}] |
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Sep 18 |
comment |
For[] or While[] can't be used inside Manipulate[]? Hehe, yeah, I know, in fact the original question isn't raised by me but I found myself unable to tell the exact reason for the problem so I turn to here…still thanks for your vivid explain for the functional programming feature of Mma! |
