interp1 - bug

[John W. Eaton]

On 12-Sep-2009, Roberto Abuter wrote:

|    I am using the most basic form of interp1 in both matlab and octave.
|    To my surprise interp1 in octave (3.0.2)  is producing some very 
| strange results on my data.
| 
|    I have a set of two vectors X, Y where X has a sawtooth shape (4 
| repetitions) and Y has 4 repetitions of an increasing/decreasing 
| amplitude sine wave.
|    to start very simple I just check the interp1 engine by making :
|   
|    XI = X;
|    YI = interp1(X,Y,XI)
| 
| 
|    to my surprise, the result YI  comes out not identical to Y .  
|   
|    well, if I try to interp1 with XI as my target grid ( a regular one 
| ) I get absolutely wierd results.
| 
| hope someone can give me a hint.

Is X monotonically increasing (or decreasing)?  From your description
it sounds like it is not.

If you think you've found a bug, then please include enough
information so that someone can reproduce precisely what you are
doing and report it to address@hidden

In any case, there is no need to cross post to both the bug and help
lists.

jwe