[Octave-bug-tracker] [bug #33292] trapz on matrices does not allow a vector as first argument

[Helios De Rosario]

URL:
  <http://savannah.gnu.org/bugs/?33292>

                 Summary: trapz on matrices does not allow a vector as first
argument
                 Project: GNU Octave
            Submitted by: heliosdr
            Submitted on: Wed May 11 17:02:02 2011
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Helios De Rosario
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.4
        Operating System: Microsoft Windows

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Details:

According to documentation, the trapz function (and cumtrapz as well) assumes
an equally spaced vector as first argument _x_, if it is ommited in the call.
Thus, I expected the function to work when a vector is explicitly entered,
even though the second argument is a matrix (whenever its first non-singleton
dimension is equal to the lenght of _x_).

However, that does not work (unlike in MATLAB):


x = linspace(0,1,100)';
y = [x, 2*x, x.^2];
intg = cumtrapz(x,y);


That can be easily solved by automatically expanding _x_ to match the
dimensions of _y_.




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