Re: Can somebody integrate this function ?
- To: mathgroup at smc.vnet.net
- Subject: [mg112536] Re: Can somebody integrate this function ?
- From: Emu <samuel.thomas.blake at gmail.com>
- Date: Sun, 19 Sep 2010 05:37:45 -0400 (EDT)
- References: <i727ib$esu$1@smc.vnet.net>
On Sep 18, 9:24 pm, c r <riemannchristof... at gmail.com> wrote:
> Can somebody try this in your version of Mathematica ?
>
> Integrate[(5/12) (-1 + z) (y^2 - 3 z^2) (27 y^4 - 12 Sqrt[3] y^5 +
> 4 y^6 + 18 y^2 (3 - 2 z) z^2 + 3 (3 - 2 z)^2 z^4 +
> 4 Sqrt[3] y^3 z^2 (-3 + 2 z)), z]
>
> Something is definitely wrong with my version of Mathematica (7).
Here's an alternative answer
In[10]:= integrand = (5/12)*(-1 + z)*(y^2 - 3*z^2)*(27*y^4 -
12*Sqrt[3]*y^5 + 4*y^6 + 18*y^2*(3 - 2*z)*z^2 +
3*(3 - 2*z)^2*z^4 + 4*Sqrt[3]*y^3*z^2*(-3 + 2*z));
In[11]:= Risch[integrand, z]
Out[11]= -((45 y^6 z)/4) + 5 Sqrt[3] y^7 z - (5 y^8 z)/3 + (
45 y^6 z^2)/8 - 5/2 Sqrt[3] y^7 z^2 + (5 y^8 z^2)/6 + (
15 y^4 z^3)/4 - (10 y^5 z^3)/Sqrt[3] + (5 y^6 z^3)/3 + (
15 y^4 z^4)/16 + (5 y^5 z^4)/Sqrt[3] - (5 y^6 z^4)/4 + (
45 y^2 z^5)/4 - 3 Sqrt[3] y^3 z^5 - 3 y^4 z^5 + (
2 y^5 z^5)/Sqrt[3] - (115 y^2 z^6)/8 + (25 y^3 z^6)/(2 Sqrt[3]) + (
135 z^7)/28 + (25 y^2 z^7)/7 - 10/7 Sqrt[3] y^3 z^7 - (
315 z^8)/32 + (5 y^2 z^8)/8 + (20 z^9)/3 - (3 z^10)/2
In[12]:= D[%, z] -
5/12 (-1 + z) (y^2 - 3 z^2) (27 y^4 - 12 Sqrt[3] y^5 + 4 y^6 +
18 y^2 (3 - 2 z) z^2 + 3 (3 - 2 z)^2 z^4 +
4 Sqrt[3] y^3 z^2 (-3 + 2 z)) // Together
Out[12]= 0
In[13]:= PolynomialQ[%%, z]
Out[13]= True
Note that the answer from Integrate is correct.
In[17]:= Integrate[integrand, z];
In[18]:= D[%, z] - integrand // Simplify
Out[18]= 0