Parametrised surfaces

<BODY bgcolor="#e7e7d6" text="#000000" link="#9944EE" vlink="#0000ff" alink="#527b29"> <P> Sorry, this requires a browser that supports frames! <BR> Try <A HREF="pag12_ct.htm">pag12_ct.htm</A> instead.</P> <HR> <ADDRESS> Ross Moore 1999-07-16 </ADDRESS>