       Bug in Mathematica 7.0.1 multiple integration?

• To: mathgroup at smc.vnet.net
• Subject: [mg116268] Bug in Mathematica 7.0.1 multiple integration?
• From: Scott Hemphill <hemphill at hemphills.net>
• Date: Wed, 9 Feb 2011 02:10:03 -0500 (EST)

```I just observed this in a naive method for calculating the volume of a
hypersphere.  It works for n = 1..4, but fails for n greater than 4:

Mathematica 7.0 for Linux x86 (64-bit)

In:= n=5

Out= 5

In:= vars = Table[Symbol["x"<>ToString[k]],{k,n}]

Out= {x1, x2, x3, x4, x5}

In:= lims = Sqrt[Table[1-Take[vars,k-1].Take[vars,k-1],{k,n}]]

2              2     2              2     2     2
Out= {1, Sqrt[1 - x1 ], Sqrt[1 - x1  - x2 ], Sqrt[1 - x1  - x2  - x3 ],

2     2     2     2
>    Sqrt[1 - x1  - x2  - x3  - x4 ]}

In:= args = Table[{vars[[k]],-lims[[k]],lims[[k]]},{k,n}]

2              2
Out= {{x1, -1, 1}, {x2, -Sqrt[1 - x1 ], Sqrt[1 - x1 ]},

2     2              2     2
>    {x3, -Sqrt[1 - x1  - x2 ], Sqrt[1 - x1  - x2 ]},

2     2     2              2     2     2
>    {x4, -Sqrt[1 - x1  - x2  - x3 ], Sqrt[1 - x1  - x2  - x3 ]},

2     2     2     2              2     2     2     2
>    {x5, -Sqrt[1 - x1  - x2  - x3  - x4 ], Sqrt[1 - x1  - x2  - x3  - x4 ]}}

In:= Integrate @@ Prepend[args,1]

Out= 0

Scott
--
Scott Hemphill	hemphill at alumni.caltech.edu
"This isn't flying.  This is falling, with style."  -- Buzz Lightyear

```

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