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