[Octave-bug-tracker] [bug #32275] "surf" function incorrectly handles NaN in colour data

[Ben Abbott]

Follow-up Comment #3, bug #32275 (project octave):

The surface's properties under Matlab are

                   AlphaData: 1
            AlphaDataMapping: 'scaled'
                  Annotation: [1x1 hg.Annotation]
                       CData: [4x5 double]
                CDataMapping: 'scaled'
                 DisplayName: ''
                   EdgeAlpha: 1
                   EdgeColor: [0 0 0]
                   FaceAlpha: 1
                   FaceColor: 'flat'
                   LineStyle: '-'
                   LineWidth: 0.5000
                      Marker: 'none'
             MarkerEdgeColor: 'auto'
             MarkerFaceColor: 'none'
                  MarkerSize: 6
                   MeshStyle: 'both'
                       XData: [4x5 double]
                       YData: [4x5 double]
                       ZData: [4x5 double]
                FaceLighting: 'flat'
                EdgeLighting: 'none'
            BackFaceLighting: 'reverselit'
             AmbientStrength: 0.3000
             DiffuseStrength: 0.6000
            SpecularStrength: 0.9000
            SpecularExponent: 10
    SpecularColorReflectance: 1
               VertexNormals: [4x5x3 double]
                  NormalMode: 'auto'
                BeingDeleted: 'off'
               ButtonDownFcn: []
                    Children: [0x1 double]
                    Clipping: 'on'
                   CreateFcn: []
                   DeleteFcn: []
                  BusyAction: 'queue'
            HandleVisibility: 'on'
                     HitTest: 'on'
               Interruptible: 'on'
                    Selected: 'off'
          SelectionHighlight: 'on'
                         Tag: ''
                        Type: 'surface'
               UIContextMenu: []
                    UserData: []
                     Visible: 'on'
                      Parent: 174.0011
                   XDataMode: 'manual'
                 XDataSource: ''
                   YDataMode: 'manual'
                 YDataSource: ''
                   CDataMode: 'manual'
                 CDataSource: ''
                 ZDataSource: ''


I don't think anything too complicated is needed. My understanding is that the
NaN value should be equivalent to "none".

For gnuplot, I think the NaNs can be intereprted as missing values. See the
thread below (I haven't looked to see if this works for gnuplot)

http://objectmix.com/graphics/139704-management-not-number-fields.html

Two solutions are mentioned.


set datafile missing "NaN"


I'm not sure if this will work for us. The second solution implied the "using"
specifier can fix this problem, but I don't undertand how.


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