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6h
revised Reproducing Mathematica's Nullspace basis within c++
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23h
comment UnitaryMatrixQ function not returning true for a unitary matrix
@Xavier While sometimes annoying, these Automatic settings are understandable. They want to provide a reasonable default for users, depending on the input. I just implemented a Method option for a shortest path function in IGraph/M today. The default is Automatic and the method it chooses depends on whether the graph is weighted or not, whether there are any negative weights, and the size of the graph. Overall it tries to choose the fastest way that is likely to work well.
23h
comment UnitaryMatrixQ function not returning true for a unitary matrix
@Xavier In practice Automatic means that it could be anything. It could be as simple as SameQ or Equal or it could be a custom function not available to us users. This is pretty common (and pretty annoying) with Mathematica. One example is the ComplexityFunction option of Simplify. People have been asking about this so much that they finally included it in the documentation. But Automatic generally means: unknown unless explicitly documented. My guess is that it's not a single function but selected based on the type of matrices. It is likely different for numeric and symbolic.
23h
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1d
revised Reproduce image effect in Mathematica
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1d
revised Reproduce image effect in Mathematica
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1d
comment Reproduce image effect in Mathematica
@macurie One more note: do not export by right-click -> Save Graphics As... You must use the Export command to make sure the effect disappears.
1d
comment Reproduce image effect in Mathematica
@macurie I cannot see this on my high-res screen but I think I know what you mean. Mathematica tends to round everything to screen pixels, which can induce the moire-like effect you describe. Export the graphics to PDF, and view it with a PDF viewer. Alternatively export it to a bitmap at very high resolutions and downscale it to a a more reasonable size. The effect should disappear.
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comment ImageSize as absolute (metric) value
@Kuba There's also an in-notebook ruler: mathematica.stackexchange.com/a/750/12
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answered Reproduce image effect in Mathematica
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comment ImageSize as absolute (metric) value
@Kuba The ImageResolution option can change this 72. It has to be used in Rasterize or Export. Another thing: do not use ImageSize in Export, use it instead as a Graphics option to get the desired result. Export[..., g, ImageSize -> ..., ImageResolution -> ...] is bad. Export[..., Show[g, ImageSize -> ...], ImageResolution -> ...] is good. At least for bitmap formats like PNG. But I don't understand why!
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comment ImageSize as absolute (metric) value
@Kuba When exporting graphics, it's true (with default settings) that pp = px. But I am not certain about exporting other notebook objects, such as Row, Column or Legended (!!!). I think Mma was using the "Printout" environment for notebook objects which has a smaller-than-one scaling factor by default. I don't remember the details, but I know Alexey Popkov had either a question or answer (or both?) on this topic (shrinkage with Printout environment).
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comment Small World network on a square grid
@ResidentStiefel Let me know if you have any trouble with IGraph/M! What OS are you using?
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revised Small World network on a square grid
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revised Small World network on a square grid
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comment Small World network on a square grid
Marginal to your question, but it's good to not that if you start with the grid shown here, the rewired networks will not have the small world property as originally defined by Watts and Strogatz because a simple lattice like this does not have a high clustering coefficient.
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revised Small World network on a square grid
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