catdef: division by zeroError detected within library code:
catdef: division by zeroError detected within library code:
integrate: implementation incomplete (residue poly has multipleError detected within library code:
On 2/9/2024 11:23 AM, clicliclic@freenet.de wrote:
I have been playing around with some old algebraic integrands in the
new version 1.3.10 of FriCAS on the web interface.
Sam Blake's pseudo-elliptic of April 2020 still gives:
integrate((x^4 - 1)*(x^4 + x^2 + 1)*sqrt(-x^4 + x^2 - 1)
/(x^4 + 1)^3, x)
catdef: division by zeroError detected within library code:
perhaps because the radicand is negative everywhere on the real
axis.
Fyi;
I've reported division by zero to Fricas newsgroup
https://groups.google.com/g/fricas-devel/c/6g0B53qX2TU
Btw, I do not think many Fricas developers read sci.math.symbolic
May be you could CC
fricas-devel@googlegroups.com
also. I do not know if it will work or not from your end
or if registration is needed or not. Sometimes I get direct email
from the above myself.
And an older and presumably truly elliptic case still fails:
integrate((5*x - 9*sqrt(6) + 26)
/((x^2 - 4*x - 50)*sqrt(x^3 - 30*x - 56)), x)
catdef: division by zeroError detected within library code:
in the same manner, although the radicand is cubic here.
[...]
And for the next integrand, FriCAS still produces unreasonable
integers in an arc tangent's argument:
integrate(1/((x + 1)*(x^3 + 2)^(1/3)), x)
... while the antiderivative can in fact be compactly stated as:
INT(1/((x + 1)*(x^3 + 2)^(1/3)), x) =
1/12*(- 3*LN((x^3 + 2)^(1/3) - x)
+ 2*SQRT(3)*ATAN(1/SQRT(3)*(1 + 2*x/(x^3 + 2)^(1/3))))
- 1/4*(LN((x + 2)^3 - (x^3 + 2))
- 3*LN((x + 2) - (x^3 + 2)^(1/3))
+ 2*SQRT(3)*ATAN(1/SQRT(3)*(1 + 2*((x + 2)/(x^3 + 2)^(1/3)))))
If the unreasonable numbers cannot be avoided earlier, they could at
least be removed by subtracting an arc tangent for a suitably chosen
value of x; both x = infinity and x = -2^(1/3) turn out to work
well.
[...]
"Nasser M. Abbasi" schrieb:98966744593197647869364591874*x^4+190053406517364372745124029472*x^3+(-642339750020464731448133545632)*x^2+(-1764382450892402509391037276448)*x+(-1072244631963565627440642667696))*3^(1/2)*((x^3+2)^(1/3))^2+((-45228634350310035870300951616)*x^5+(-
On 2/9/2024 11:23 AM, clicliclic@freenet.de wrote:
And for the next integrand, FriCAS still produces unreasonable
integers in an arc tangent's argument:
integrate(1/((x + 1)*(x^3 + 2)^(1/3)), x)
(log(((21*x^4+(-6)*x^3+(-96)*x^2+(-60)*x+12)*((x^3+2)^(1/3))^2+(21*x^5+(-48)*x^3+102*x^2+228*x+96)*(x^3+2)^(1/3)+(22*x^6+6*x^5+(-48)*x^4+44*x^3+24*x^2+(-192)*x+(-140)))/(x^6+6*x^5+15*x^4+20*x^3+15*x^2+6*x+1))+2*3^(1/2)*atan(((
... while the antiderivative can in fact be compactly stated as:
INT(1/((x + 1)*(x^3 + 2)^(1/3)), x) =
1/12*(- 3*LN((x^3 + 2)^(1/3) - x)
+ 2*SQRT(3)*ATAN(1/SQRT(3)*(1 + 2*x/(x^3 + 2)^(1/3))))
- 1/4*(LN((x + 2)^3 - (x^3 + 2))
- 3*LN((x + 2) - (x^3 + 2)^(1/3))
+ 2*SQRT(3)*ATAN(1/SQRT(3)*(1 + 2*((x + 2)/(x^3 + 2)^(1/3)))))
If the unreasonable numbers cannot be avoided earlier, they could
at least be removed by subtracting an arc tangent for a suitably
chosen value of x; both x = infinity and x = -2^(1/3) turn out to
work well.
I also find that x = -1 works less well; perhaps one should simply try
x = infinity in all cases of algebraic antiderivatives with
unreasonable arc tangent arguments (but only if the radical stays
real?), and perhaps for reasonable arguments as well to avoid deciding
what's unreasonable.
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