# Volume form not what I expected.

Hello everyone,

Let us suppose I want to create a finite element representation of half-sphere of radius one, where the surface is described by a 3-component vector phi = (X, Y, Z). I then wish to compute the volume of this half-sphere.

Here is a minimal example:

# Begin

from dolfin import *

mesh = UnitCircle(7) # I'm aware that this is deprecated, but I can't recall the new syntax

space= VectorFunctionS

class phiexpression(

def eval(self,

values[0] = x[0]

values[1] = x[1]

values[2] = sqrt(abs(

def value_shape(self):

return (3,)

phi = Function(space)

phiexp = phiexpression()

phi.interpolate

V = (1./3)*

initial_

print initial_

# End

Now, this ought to give me 2 pi / 3, but instead I get 1.92919724808

What am I doing wrong? Is this just round-off error?

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- Christopher Laing

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