splineDiff

import almafa.engine.func-1;


  xy = [-100,4; 8,93; 42,-88; 444, 827];
  xmin = min(xy[...;0]);
  xmax = max(xy[...;0]);
  eps = (xmax-xmin)/200;
  xmin -= 2*eps;
  xmax += 2*eps;
  x = xmin..eps..xmax;

  p = splineInterp(xy);
  print("The interpolating normal cubic spline.").title()
  plot(x, (@(x) splineEval(p,x))(#x));
  print("Its derivative.").title()
  plot(x, (@(x) splineEval(splineDiff(p),x))(#x))
  print("Its 2nd derivative.").title()
  plot(x, (@(x) splineEval(splineDiff(p,2),x))(#x))
  print("Its 3rd derivative.").title()
  plot(x, (@(x) splineEval(splineDiff(p,3),x))(#x))

s	The spline to be differentiated.
n	(Optional, defaults to 1) The order of differentiation.
return value	The derivative.

splineDiff(s, n)