Daniel Lichtblau
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34,670
125/100 score
 11m comment PolynomialExtendedGCD in 2 variables (2) Yes, it's possible to get an extended gcd for polynomials in A[x] where A=Q[y]/. Would take some work, but its possible. For the specil case where the irreducible is linear, just do substitution as I noted in an earlier comment. 13m comment PolynomialExtendedGCD in 2 variables (1) Your second question amounts to doing the computation after substituting y->1. Which in turn reduces to an extended gcd in one variable, over the rationals. 21h comment Series Soln False error What do you suppose y(0)==1 will do? 23h comment A question on JordanDecomposition in Mathematica No, not possible. 1d comment Definite integration in mathematica @march That blog is here. In this case the one sided limits at the pole will cancel, so it is in a sense "the right thing to do". Setting PrincipalValue -> True in the definite integral should also work, in theory, but it was taking more time than I wanted to wait so I aborted it. 1d comment Measuring space complexity? I don't know of any such. I generally double size 2-3 times, checking MemoryInUse/MaxMemoryUsed and/or LeafCount depending on whether it is intermediate usage or size of result that I'm more interested in. 1d comment Complex limit gives wrong answer Exactly right (and an upvote). 1d comment Definite integration in mathematica Mathematica claims the integral diverges because, well, it diverges. So that's not a good way to get the Fourier transform of 1/(x^2-b^2). To get the FT one can do In[14]:= FullSimplify[ Sqrt[2*Pi]* FourierTransform[1/(x^2 - b^2), x, a, Assumptions -> {a > 0, b != 0, Element[b, Reals]}]] Out[14]= -((\[Pi] Sin[a b])/b) 1d comment What's the easiest way to find the closest point in a list of pairs? @ciao Having worked on that code a bit, I of course had no idea the Automatic setting would do just what was wanted. 1d comment What's the easiest way to find the closest point in a list of pairs? If you are going to do this often, with the same list, then create a NearestFunction with Nearest[testdat2[[All, 1]]->Range[Length[testdat2]]]. You should now be able to avoid the Position machinations. For one-off purposes, the method in a response that uses Ordering is quite fine. 1d comment Huge difference after changing a fraction to decimal Possibly shows a bug in Series handling of HypergeometricPFQ at infinity, when input to PFQ is approximate. 1d comment Huge difference after changing a fraction to decimal Well...1.000000000001^n/1.^n and .9999999999999^n/1.^n also have very different behaviors as n gets large. The differing forms of integral strike me as being similar in spirit to this situation. 1d comment Huge difference after changing a fraction to decimal @LLlAMnYP Mathematica gives a result for the integral. Then claims the limit diverges for decimal input. No bug there. 1d comment Can you help me reduce this? WolframAlpha's search bar has a character limit I'm voting to close this question as off-topic because it pertains to Wolfram|Alpha rather than Mathematica. 2d comment NRoots Results: From Equations to List of Root Values Use ToRules (as noted in Roots ref guide page, Properties & Relations). Apr 27 comment Why does the following integral generate an error message for Delete::partw and IntegrateImproperDumptmp The messages comprise a small bug. Will be fixed. Apr 27 comment Subscripted variables give errors in Module expression The error message pretty much answers the question implicit in the subject header. Apr 26 comment Reduce expressions modulo quadratic monomials more efficiently? (2) Without a complete self contained example it is unlikely that you will get very usable suggestions, unless by accident. It is difficult to craft efficient code for purposes that are underspecified and in the absence of anything on which to test it. Apr 26 comment Reduce expressions modulo quadratic monomials more efficiently? (1) Have a look at documentation for PolynomialReduce (which is part of the functionality designed for working in quotient rings). Apr 26 revised Kernel crashes when computing finite difference mixed derivative with respect to y & z but works fine when computing with respect to x & y or x & z? edited tags