[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: interp1  bug
From: 
John W. Eaton 
Subject: 
Re: interp1  bug 
Date: 
Sat, 12 Sep 2009 08:04:07 0400 
On 12Sep2009, Søren Hauberg wrote:
 lør, 12 09 2009 kl. 13:41 +0200, skrev Roberto Abuter:
 > I guess it is just a difference in behavior between Matlab and Octave.
 > one can always reshuffle (X,Y) in such a way X becames monotonic.

 Is there any particular reason why we are not doing this in 'interp1'?
 Couldn't just add

 [x, idx] = sort (x);
 y = y (idx);

 to 'interp1' ?
Suppose I have a set of points that approximate a circle:
theta = 0:0.2:2*pi;
x = cos(theta);
y = sin(theta);
plot (x, y);
and I want to interpolate between two of these points. If I leave the
points ordered as they are, I need to pick a range where the
interpolation will make sense. If I just blindly sort the X and Y
values, I get something that doesn't look a lot like a circle, so
interpolating between two of the points is not likely to give me the
result I'm looking for:
[x, idx] = sort (x);
y = y (idx);
plot (x, y);
jwe