SPLINE	Cubic spline data interpolation.
 	Given data vectors X and Y, and a new abscissa vector XI, the
 	function YI = SPLINE(X,Y,XI) uses cubic spline interpolation
 	to find a vector YI corresponding to XI.
 
 	Here's an example that generates a coarse sine curve, then
 	interpolates over a finer abscissa:
 
 	    x = 0:10;  y = sin(x);
 	    xi = 0:.25:10;
 	    yi = spline(x,y,xi);
 	    plot(x,y,'o',xi,yi)
 
 	PP = spline(x,y) returns the pp-form of the cubic spline interpolant
 	instead, for later use with  ppval, etc.
 
 	See also INTERP1, INTERP2, PPVAL, MKPP, UNMKPP, the Spline Toolbox.


 PPVAL	Evaluate piecewise polynomial.
 
 	  v = ppval(pp,xx)
 
 	returns the value of the pp function  pp  at  xx.
 
 	See also MKPP, UNMKPP, SPLINE.

 MKPP	Make piece-wise polynomial.  
 
 	   pp = mkpp(breaks,coefs)
 
 	puts together a pp function from the breaks and coefficients input or
 	requested. The number  l  of polynomial pieces is determined as
 	     l := length(breaks)-1 .
 	The  order  k  of the pp is obtained as
 	     k := length(coefs)/l ,
 	and this ratio had better be an integer. 
 	See also UNMKPP, PPVAL, SPLINE.

 UNMKPP	Supply details about piecewise polynomial.
 
 	    [breaks,coefs,l,k] = unmkpp(pp)
 
 	takes apart the  pp  function into its pieces.
 	See also MKPP, SPLINE, PPVAL.