When simpver = NULL
, the volume formula (\(V\)) of the explicit Preston equation is selected:
$$ V(x) = \frac{4\,\pi}{315}a\,b^{2}\left(105+21\,c_{1}^{2}+42\,c_{2}+9\,c_{2}^2+18\,c_{1}\,c_{3}+5\,c_{3}^2\right), $$
where P
has five parameters: \(a\), \(b\), \(c_{1}\), \(c_{2}\), and \(c_{3}\).
\(\quad\) When simpver = 1
, the volume formula of the simplified version 1 is selected:
$$ V(x) = \frac{4\,\pi}{315}a\,b^{2}\left(105+21\,c_{1}^{2}+42\,c_{2}+9\,c_{2}^2\right), $$
where P
has four parameters: \(a\), \(b\), \(c_{1}\), and \(c_{2}\).
\(\quad\) When simpver = 2
, the volume formula of the simplified version 2 is selected:
$$ V(x) = \frac{4\,\pi}{315}a\,b^{2}\left(105+21\,c_{1}^{2}\right), $$
where P
has three parameters: \(a\), \(b\), and \(c_{1}\).
\(\quad\) When simpver = 3
, the volume formula of the simplified version 3 is selected:
$$ V(x) = \frac{4\,\pi}{315}a\,b^{2}\left(105+42\,c_{2}+9\,c_{2}^2\right), $$
where P
has three parameters: \(a\), \(b\), and \(c_{2}\).