Keeping it single valued

[David Arnold <dwarnold45@suddenlink.net>]

All,

This example from the Metapost manual is beyond my expertise. The  
second figure is sweet, just what I would want. Can anyone wax  
philosophic for a bit and explain why the y-scaling keeps the second  
function single valued?

starttext

\startbuffer[figure]
numeric scf, t[];
3.2scf=2.4in;
path fun;
fun:=(0,-1)..(1,.5){right}..(1.9,.2){right}..{curl .1}(3.2,2);
fun:=fun scaled scf;
draw fun;
\stopbuffer

\placefigure
[][fig:one]
{Caption.}
{\processMPbuffer[figure]}

\startbuffer[figure]
numeric scf, yscl, t[];
3.2scf=2.4in;
path fun;
yscl=.1;  %keep the function single valued
fun:=(0,-1yscl)..(1,.5yscl){right}..(1.9,.2yscl){right}..{curl .1} 
(3.2,2yscl);
fun:=fun yscaled (1/yscl);
fun:=fun scaled scf;
draw fun;
\stopbuffer

\placefigure
[][fig:one]
{Caption.}
{\processMPbuffer[figure]}

\stoptext