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igraph / xdata-igraph

xdata igraph, has been merged into igraph/igraph
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ASE: use eigendecomposition for undirected graphs #44

Closed gaborcsardi closed 10 years ago

gaborcsardi commented 10 years ago

From #42.

gaborcsardi commented 10 years ago

This actually brings up some issues, e.g. we cannot scale using the square root of the eigenvalues any more, as they are not guaranteed to be non-negative. Should the user get an error message if scaled=TRUE and the graph is undirected?

dpmcsuss commented 10 years ago

Usually we take the square root of absolute values. Additionally, this should not come up very often in the largest algebraic setup.

For Largest Magnitude, It might be useful to return the eigenvalues in the output list since then people can check their signs if necessary.