[Octave-bug-tracker] [bug #40825] interp1 "linear" fails when x has jumps and y is multi-column

[Juan Pablo Carbajal]

URL:
  <http://savannah.gnu.org/bugs/?40825>

                 Summary: interp1 "linear" fails when x has jumps and y is
multi-column
                 Project: GNU Octave
            Submitted by: juanpi
            Submitted on: Fri 06 Dec 2013 02:07:33 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: juanpi
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

Hi,

This is somehow related with this bug
https://savannah.gnu.org/bugs/?func=detailitem&item_id=36732

The problem arises when interp1 fixes the input data due to jumps but mkpp
doesn't know about it.

Example

t  = [0 1 1 2 3]'; 
x  = t;
ti = [0.5 1.5 2.5]';
interp1(t,x,ti); # works fine (reshape in mkpp line 78 is valid)
interp1(t,[x x],ti); # fails cause length is not multiple of szy(2) (line 252
in interp1)


The removal of jumps in lines 246-250 of interp1.m has to be consistent with
multi-column inputs.

In the next post I will attach a change that may solve the problem. I am
copying the data vector y cause I do not know if forward in the future it is
used, I just followed the same policy as for x (copied to xx)







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