397cfa61dd
Database tüddelei DBHanlder läuft gut für DIESE Datanbank struktur... App begonnen aber weit entfernt von gutem Stand
39 lines
1.9 KiB
Plaintext
39 lines
1.9 KiB
Plaintext
{\rtf1\mac\ansicpg10000\cocoartf102
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{\fonttbl\f0\fswiss\fcharset77 Helvetica;}
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{\colortbl;\red255\green255\blue255;}
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\margl1440\margr1440\vieww10780\viewh13720\viewkind0
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\pard\tx720\tx1440\tx2160\tx2880\tx3600\tx4320\tx5040\tx5760\tx6480\tx7200\tx7920\tx8640\ql\qnatural
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\f0\fs24 \cf0 Nomination comments:\
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\
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Inpaint_nans fills a hole in matlab. (Yes, the pun was intentional.) But there\
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is indeed a niche that inpaint_nans falls into.\
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\
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The alternative to inpaint_nans is griddata (interp1 can be used for the 1-d \
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problems) but griddata fails to extrapolate well. Griddata also has serious\
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problems when its data already lies on a grid, due to its use of a Delaunay \
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triangulation. The other serious problem with the use of griddata is the\
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triangulation itself. The shape of the hole to be filled can sometimes result\
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in triangles with a poor aspect ratio (long, thin triangles) which are in turn\
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poor for interpolation. In fact, Griddata can even leave interior points\
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uninterpolated (see the tests.)\
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\
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A future plan for inpaint_nans is to add an option that will use a locally\
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anisotropic membrane model. This will allow better modeling for certain\
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classes of wavy surfaces. I'm also highly tempted to remove method 5.\
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I've never really liked it, having put it in at the request of one user. It has\
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no valid theory behind it in the context of inpaint_nans.\
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\
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In the interest of openness, I'll also say what inpaint_nans does not do. It\
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does not handle non-uniform grids. It is limited by the amount of memory \
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in the size of the arrays it can handle, although some of the methods were\
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explicitly provided to be more memory efficient than others. Inpaint_nans\
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also makes heavy use of sparse matrices, so surprisingly large problems\
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are accessible.\
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\
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Finally, while inpaint_nans does work for 1-d problems, they are not my\
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target. Interp1 (with 'spline' as the method) is as accurate, and should be\
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faster in general.\
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\
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John\
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} |