Scalar- and Planar- Valued Curve Fitting Using Splines Under Tension
The spline under tension was introduced by
Schweikert in an attempt to imitate cubic splines 
but avoid the spurious critical points they induce. 
The defining equations are presented here, together 
with an efficient method for determining the necessary
parameters and computing the resultant spline. 
 The standard scalar-valued curve fitting problem is discussed,
as well as the fitting of open and closed 
curves in the plane.  The use of these curves and the
importance of the tension in the fitting of contour 
lines are mentioned as application.
CACM April, 1974
Cline, A. K.
