[Octave-bug-tracker] [bug #39574] spline produces incorrect results in the 'complete' situation

[Andreas Stahel]

URL:
  <http://savannah.gnu.org/bugs/?39574>

                 Summary: spline produces incorrect results in the 'complete'
situation
                 Project: GNU Octave
            Submitted by: sha1
            Submitted on: Fri 26 Jul 2013 04:03:57 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Andreas Stahel
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: GNU/Linux

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Details:

Dear developers

The two codes code below should produce identical results.
spline() (and csape() from the splines package) fail
if three points and the derivatives at the boundary are supplied.
Matlab produces the expected result

x = linspace(0,pi/2,3); y = sin(x);
t = linspace(0,pi/2);

ys = spline(x,y,t);  % is OK
plot(t,ys)
ys = spline(x,[1 y 0],t);  % is not OK
plot(t,ys)


Thank you for the good work

Andreas




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