Rik, can you or someone else check the following against your newly pushed quadcc? this throws an error in the 4.2,1 release version. unless it's something now fixed in your version I think it calls for a bug report. I stumbled on it when I tried to pass a function of x only to integral2: ans = 1>> quadv(@(x) 1, 0,1) >> quad(@(x) 1, 0,1) ans = 1 >> quadgk(@(x) 1, 0,1) ans = 1 >> quadcc(@(x) 1, 0,1) error: quadcc: integrand F must return a single, real-valued vector _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
NJank wrote
> Rik, can you or someone else check the following against your newly pushed > quadcc? this throws an error in the 4.2,1 release version. unless it's > something now fixed in your version I think it calls for a bug report. I > stumbled on it when I tried to pass a function of x only to integral2: > >>> quadv(@(x) 1, 0,1) > ans = 1 >>> quad(@(x) 1, 0,1) > ans = 1 >>> quadgk(@(x) 1, 0,1) > ans = 1 >>> quadcc(@(x) 1, 0,1) > error: quadcc: integrand F must return a single, real-valued vector > > _______________________________________________ > Help-octave mailing list > Help-octave@ > https://lists.gnu.org/mailman/listinfo/help-octave Hi, This error is still present on the development branch but if I understand the documentation correctly, it is expected: >> The function F must be vectorized and must return a vector of output >> values if given a vector of input values So the correct call form should be something like quadcc (@(x) ones (size (x)), 0,1) Pantxo -- Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
On Fri, Sep 29, 2017 at 9:35 AM, Pantxo <[hidden email]> wrote: NJank wrote understood. but quadgk is also has the same requirement, but doesn't choke on the function. what does it do differently? _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
In reply to this post by NJank
On 09/29/2017 05:27 AM, Nicholas Jankowski wrote:
> Rik, can you or someone else check the following against your newly > pushed quadcc? this throws an error in the 4.2,1 release version. unless > it's something now fixed in your version I think it calls for a bug > report. I stumbled on it when I tried to pass a function of x only to > integral2: > > >> quadv(@(x) 1, 0,1) > ans = 1 > >> quad(@(x) 1, 0,1) > ans = 1 > >> quadgk(@(x) 1, 0,1) > ans = 1 > >> quadcc(@(x) 1, 0,1) > error: quadcc: integrand F must return a single, real-valued vector It throws an error, but I think it might be correct. The integrand is supposed to return a vector for vector inputs. This allows the quadrature routine to call f(x1, x2, x3, ..., xn) and get y1,y2,y3, ..., yn. Vectorization is always far faster than having to write this as a for loop from 1:n and then call the function repeatedly. Just to test, if you change the integrand to a vector function it works correctly. quadcc (@(x) ones (size (x)), 0, 1) ans = 1.00000 Cheers, Rik _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
Just to test, if you change the integrand to a vector function it works
correctly. Yes, I just find it curious that the other functions do not error on the same integrand despite having the same vector function requirements. Peeking in quadgk I assume it's because of the transform that occurs on lines 235-236, that essentially redefines the function as a vector function whether it starts as one or not. maybe similar things happen in quadl. quad and quadv don't have the same requirement. I bring this up because I was trying out some compatibility tests with integral2. Matlab gives the same vector function error as quadcc for all of its vectorized quad functions (quadgk, quadl) and integral. similar for dblquad: >> dblquad(@(x,y) x, 0,1,0,1) ans = 0.5000 >> dblquad(@(x,y) y, 0,1,0,1) Error using quad (line 70) The integrand function must return an output vector of the same length as the input vector. but not for integral2: >> integral2(@(x,y) x, 0,1,0,1) ans = 0.5000 >> integral2(@(x,y) y, 0,1,0,1) ans = 0.5000 since we switched integral2 over to using quadcc, we get the same effort as dblquad >> integral2(@(x,y) x, 0,1,0,1) ans = 0.50000 >> integral2(@(x,y) y, 0,1,0,1) error: quadcc: integrand F must return a single, real-valued vector just leave this under the category of 'undocumented matlab we aren't going to worry about'? _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
On 09/29/2017 09:27 AM, Nicholas
Jankowski wrote:
I think that's good enough for now. --Rik _______________________________________________ Help-octave mailing list [hidden email] https://lists.gnu.org/mailman/listinfo/help-octave |
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