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|    sci.math.symbolic    |    Symbolic algebra discussion    |    10,432 messages    |
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|    Message 10,020 of 10,432    |
|    Nasser M. Abbasi to antispam@math.uni.wroc.pl    |
|    Re: An algebraic integral in FriCAS    |
|    09 Apr 20 22:28:54    |
      From: nma@12000.org              On 4/9/2020 6:07 PM, antispam@math.uni.wroc.pl wrote:              >> integrate(((4+x^6)*(-4+x^4+2*x^6)*(32-14*x^4-32*x^6-4*x^8+7*x       10+8*x^12)^(1/2))/(x^9*(-2+x^6)),x);       >> ?       >> ?? >> Error detected within library code:       >> ?? integrate: implementation incomplete (residue poly has multiple       non-linear factors)       >              > The two above are known problems, each will take more work to fix.       > Actually, the first one requires reorganization of integration       > routines. The second one is king of open problem: known methods       > of solving may require prohibitivly long time and nobody knows       > of really efficient method.       >              The above comes down to separate 4 integrands              (8*Sqrt[32 - 14*x^4 - 32*x^6 - 4*x^8 + 7*x^10 + 8*x^12])/x^9              (2*Sqrt[32 - 14*x^4 - 32*x^6 - 4*x^8 + 7*x^10 + 8*x^12])/x^5              (2*Sqrt[32 - 14*x^4 - 32*x^6 - 4*x^8 + 7*x^10 + 8*x^12])/x^3 +              (3*x*Sqrt[32 - 14*x^4 - 32*x^6 - 4*x^8 + 7*x^10 + 8*x^12])/(-2 + x^6)              It seems to boild down to integrand of this pattern               sqrt(a + b*x^4 + c*x^6 + d*x^8 + e*x^10 + f*x^12)              ======================       8) -> integrate( sqrt(a + b*x^4 + c*x^6 + d*x^8 + e*x^10 + f*x^12),x)               x +--------------------------------------+        ++ | 12 10 8 6 4        (8) | \|%A f + %A e + %A d + %A c + %A b + a d%A        ++       ========================              Then I tried a simpler one with polynomial of just degree 4 under the sqrt               integrate( sqrt(a + b*x + c*x^2 + d*x^3 + e*x^4 ),x)              But it could not do it either. But Mathemtica managed to do this one       but it uses special functions EllipticF, EllipticPi, and result too       large to post. These look like really hard integrals.              Is the full Risch algorithm supposed to be able to handle these also?              --Nasser              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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