[Octave-bug-tracker] [bug #49417] ode solvers should return state at automatically selected timesteps only when invoked with only one output

[Carlo de Falco]

URL:
  <http://savannah.gnu.org/bugs/?49417>

                 Summary: ode solvers should return state at automatically
selected timesteps only when invoked with only one output 
                 Project: GNU Octave
            Submitted by: cdf
            Submitted on: Sat 22 Oct 2016 10:46:00 PM CEST
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

When invoked with only one struct output, the 
ode solvers in Matlab only return the state 
evaluated at automatically selected timesteps.

Octave on the other hand returns the solution 
at manually specified timesteps if tspan has more
than two entries.

Octave :

sol = ode45 (@(t, x) 1, [0 .4  1], 1)
sol =
  scalar structure containing the fields:
    x =
       0.00000   0.40000   1.00000
    y =
       1.0000   1.4000   2.0000
    solver = ode45


Matlab :

>> sol = ode45 (@(t, x) -10 * x, [0 .4  1], 1)
sol = 
     solver: 'ode45'
    extdata: [1x1 struct]
          x: [0 0.0201 0.1023 0.1807 0.2593 0.3380 0.4166 0.4953 0.5739 0.6525
0.7312 0.8098 0.8950 1]
          y: [1 0.8180 0.3598 0.1642 0.0748 0.0341 0.0155 0.0071 0.0032 0.0015
6.6905e-04 3.0481e-04 1.3005e-04 4.5600e-05]
      stats: [1x1 struct]
      idata: [1x1 struct]



Notice that Matlab also returns additional *undocumented*
fields in the result structure that are needed by deval.






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