cubic_spline_natural

x = [2 2.5 3 4 5 6.5 8]; y = [3 -1 3 -4 0 3 2]; Given this data use cubic_spline_natural function to construct and plot a free cubic spline with zero second derivative at two ends I tried this code below but I keep getting

xx= linspace(2,8); m = length(xx); yy=zeros(1,m); for i = 1:m; yy(i)= cubic_spline_natural(x,y,0.0,0.0,xx(i)); end Undefined function or variable 'cubic_spline_natural'. variable 'cubic_spline_natural'.

xx= linspace(2,8); m = length(xx); yy=zeros(1,m); for i = 1:m; yy(i)= cubic_spline_natural(x,y,0.0,0.0,xx(i)); end Undefined function or variable 'cubic_spline_natural'.

yyy(i)= cubic_spline_natural(x,y,0.0,0.0,xx(i)); Undefined function or variable 'cubic_spline_natural'.

Answer 1

[David Ding]

Do:

 >> which cubic_spline_natural

If the output is:

'cubic_spline_natural' not found.

Then likely you did not define this function in the first place. If this is the case, you need to write this function as it is not a MATLAB built-in function.

However, if you did, make sure that it resides in the current working directory or add the directory containing this function in your working path.

Thanks,

David