The bezier Style Option

This option defines a single command, \bezier, that draws a curved line in a picture environment. Let Pi be the point with coordinates (xi, yi), for i = 1, 2, and 3. The command
 \bezier{n}(x1,y1)(x2,y2)(x3,y3)
draws n points on the quadratic Bezier spline determined by the three points P1, P2, and P3. The locus of points on this spline is a parabolic arc from P1 to P3 having the line P1P2 tangent to it at P1 and the line P2P3 tangent to it at P3. Note that P2 is not on this arc unless P1, P2, and P3 are colinear, in which case the arc is a straight line. Bezier splines are useful because it's easy to join two of them together smoothly by giving them the same tangent line where they meet.

It takes roughly 75 points per inch to form a solid line, depending upon the line thickness. See Section C.13.3 of the manual for commands to specify line thickness in a picture environment. This command is very slow, and TEX has enough memory to hold only about 1000 points plus a page of text. (Remember that TEX keeps the current page plus all as yet unprinted figures in memory.) So, the bezier command should be used for only a small number of small curves.