Sici Spiral

$\begin{figure}\begin{center}\BoxedEPSF{SiciSpiral.epsf scaled 700}\end{center}\end{figure}$

The spiral

$\displaystyle x$	$\textstyle =$	$\displaystyle c\mathop{\rm ci}\nolimits t$
$\displaystyle y$	$\textstyle =$	$\displaystyle c(\mathop{\rm si}\nolimits t-{\textstyle{1\over 2}}\pi),$

where $\mathop{\rm ci}\nolimits (t)$ and $\mathop{\rm si}\nolimits (t)$ are the Cosine Integral and Sine Integral and

is a constant.

References

von Seggern, D. CRC Standard Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 204 and 270, 1993.