Forums before death by AOL, social media and spammers... "We can't have nice things"
|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]
|    Message 8,712 of 10,432    |
|    Albert Rich to clicl...@freenet.de    |
|    Re: comments on some IITS evaluations    |
|    15 Dec 14 13:59:09    |
      From: Albert_Rich@msn.com              On Monday, December 15, 2014 8:03:29 AM UTC-10, clicl...@freenet.de wrote:              >> Unfortunately, not using PCE will require an exponential increase in       >> the number of rules required. For example, Rubi currently has rules       >> for integrands of the form (a+b x)^m (c+d x)^n, and transforms       >> integrands of the form ((a+b x)^m (c+d x)^n)^p to that simpler form       >> using PCE. Now it will have to have explicit rules for such       >> integrands. Sigh...       >       > ... let's hope that Timofeev did a fairly thorough job.              Note quite sure of the relevance of your comment to the concern I raised over       the need for a plethora of new rules...              One solution I have considered is generalizing the existing rules to handle       non-integer powers of products of powers of linears. For example, the       existing rule              Int((a+b x)^m (c+d x)^n, x) -->        (a+b x)^(m+1) (c+d x)^n / (b (m+1)) -        d n / (b (m+1)) Int((a+b x)^(m+1) (c+d x)^(n-1), x)              needs to be generalized to              Int(((a+b x)^m (c+d x)^n)^p, x) --> ???              without use PCE. Can anyone help me out with the RHS?              > The continuitized antiderivative in Chapter 9 can be made even slightly       > simpler:       >       > INT(ASIN(SQRT(1 - x^2))/SQRT(1 - x^2), x) =       > 1/2*ASIN(x)*(pi - ASIN(SQRT(x^2)))              I find products of arcsines and arcsines of radicals objectionable. Thus I       propose               1/2*pi*arcsin(x) - 1/2*x/sqrt(x^2)*arcsin(x)^2              as the optimal antiderivative of arcsin(sqrt(1-x^2))/sqrt(1-x^2).              Albert              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]
(c) 1994, bbs@darkrealms.ca