[Octave-bug-tracker] [bug #52243] some integrators don't preserve type single

[Nicholas Jankowski]

URL:
  <http://savannah.gnu.org/bugs/?52243>

                 Summary: some integrators don't preserve type single
                 Project: GNU Octave
            Submitted by: nrjank
            Submitted on: Tue 17 Oct 2017 06:41:01 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: Nicholas Jankowski
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: other
        Operating System: Any

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Details:

many integral functions do not preserve single type in all cases.   examples
below:

matlab 2017a

>> class(quad(@sin,0,single(1)))
ans =
    'single'
>> class(quadv(@sin,0,single(1)))
ans =
    'single'
>> class(quadl(@sin,0,single(1)))
ans =
    'single'
>> class(quadgk(@sin,0,single(1)))
ans =
    'single'
>> class(quad(@sin,0,single(1)))
ans =
    'single'
>> class(integral(@sin,0,single(1)))
ans =
    'single'
>> class(integral2(@plus,1,2,single(3),4))
ans =
    'single'
>> class(dblquad(@plus,1,2,single(3),4))
ans =
    'single'
>> class(quad2d(@plus,1,2,single(3),4))
ans =
    'single'
>> class(integral3(@(x,y,z) x+y+z,1,2,1,2,single(3),4))
ans =
    'single'
>> class(triplequad(@(x,y,z) x+y+z,1,2,1,2,single(3),4))
ans =
    'single'


Octave:

>> class(quad(@sin,0,single(1)))
ans = single
>> class(quadv(@sin,0,single(1)))
ans = single
>> class(quadl(@sin,0,single(1)))
ans = double
>> class(quadgk(@sin,0,single(1)))
ans = single
>> class(quadcc(@sin,0,single(1)))
ans = double
>> class(integral(@sin,0,single(1)))
ans = single
>> class(integral2(@plus,1,2,single(3),4))
ans = single
>> class(integral3(@plus,1,2,1,2,single(3),4))
ans = double
>> class(dblquad(@plus,1,2,single(3),4))
ans = double
>> class(triplequad(@plus,1,2,1,2,single(3),4))
ans = double


Generally speaking, for matlab compatibility type single should be preserved
for any type single inputs for limits or waypoints but not for tolerances. 

so for us seems it applies to:

integral
integral2
integral3
quad2d
dblquad
triplequad
quadl
quadcc

integral passes but it has a patch waiting (bug #42073) that will have it use
quadcc. that patch has been updated to preserve single type no matter which
underlying quad is called.

the other integral functions and quad2d already do a type check, so a patch
that recasts the output as single when necessary should be easy. I can work on
a patch for those with appropriate BISTs




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