Timeline for A problem with getting a coefficient
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Oct 7, 2014 at 13:53 | vote | accept | Vladimir | ||
| Oct 6, 2014 at 19:10 | answer | added | Fred Simons | timeline score: 2 | |
| Oct 6, 2014 at 17:54 | comment | added | Daniel Lichtblau |
Possibly you can get the sort of behavior you want by using TrigExpand[ExpToTrig[expression]] and the trying to extract the coefficients of Cos[a*t] and Sin[a*t]. Another approach would be to recast as an explicit polynomial, by converting Exp[I*a*t] to a "variable" eiat and likewise for Exp[I*a*b].
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| Oct 6, 2014 at 17:36 | comment | added | Vladimir | Anyway thank you for help. I think I need to reconsider something in my program when working with exponents. The Coefficient[] does not fit to my problem because it is not a polynomial. | |
| Oct 6, 2014 at 17:28 | comment | added | Dr. belisarius |
Not to mention that you could multiply any expression by E^(a t) E(-a t). That's why it makes sense for polynomials only.
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| Oct 6, 2014 at 17:26 | comment | added | Igor Rivin | The question is whether your terms are textually explicit (if yes, it is not too hard to do with patterns, if not, it becomes a little iffy). | |
| Oct 6, 2014 at 17:24 | comment | added | Vladimir | I need to collect the coefficients of exponents with particular powers e.g. E^(I a t), E^(I b t) and so on. Now I see that it is not a Coefficient[] but any other method. Somehow I did not pay attention that Coefficient[] processes only polynomials. | |
| Oct 6, 2014 at 17:22 | comment | added | Igor Rivin | I am sure it is possible, but it may be a little painful, the question is: what is it you are really trying to do? | |
| Oct 6, 2014 at 17:20 | comment | added | Vladimir | @IgorRivin So is it possible to do what I want? | |
| Oct 6, 2014 at 17:19 | comment | added | Igor Rivin |
Since the documentation on Coefficient[] speaks of polynomials only, why do you expect anything sensible?
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| Oct 6, 2014 at 17:08 | history | asked | Vladimir | CC BY-SA 3.0 |