I need the equation or systems of equations for the Trefoil knot. Thanks.

Questions
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1

My name is Gregg Standage and I am writing a paper on the organization of the pulvinar nucleus of the thalamus in old world primate brains.
I was trained as a physician scientist and have both MD and Ph.D. degrees. I need the equation or systems of equations needed to describe the trefoil knot,and if possible the figure eight knot. I need to use them as examples in the paper. If anyone could provide me with this information it would be much appreciated. Thank you.

2 
http://en.wikipedia.org/wiki/Trefoil_knot

In[1]:= ParametricPlot3D[{Sin[t] + 2 Sin[2 t], Cos[t] - 2 Cos[2 t], -Sin[3 t]}, {t, 0, 2 Pi}]

Out[1]= ...PlotSnipped...

http://en.wikipedia.org/wiki/Figure-eight_knot_(mathematics)

In[3]:= ParametricPlot3D[{(2 + Cos[2 t]) Cos[3 t], (2 + Cos[2 t]) Sin[3 t], Sin[4 t]}, {t, 0, 2 Pi}]

Out[3]= ...PlotSnipped...

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