For natural cubic splines the spline basis functions are only shown on the interval (boundary knot 1, boundary knot 2). I would suggest to fix the x-axis range also for the spline basis functions with (21,80) and show the spline basis functions on the full range.
For natural cubic splines the spline basis functions are only shown on the interval (boundary knot 1, boundary knot 2). I would suggest to fix the x-axis range also for the spline basis functions with (21,80) and show the spline basis functions on the full range.