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Bug 1334 - Shorthand indexing for vectors
Summary: Shorthand indexing for vectors
Status: RESOLVED DUPLICATE of bug 329
Alias: None
Product: Eigen
Classification: Unclassified
Component: Core - general (show other bugs)
Version: unspecified
Hardware: All All
: Normal Feature Request
Assignee: Nobody
Depends on:
Reported: 2016-10-25 19:44 UTC by Darcy
Modified: 2019-12-04 16:28 UTC (History)
3 users (show)


Description Darcy 2016-10-25 19:44:46 UTC
Requested feature:

Suppose we have an array of indices which correspond to indices in a numerical array (gather type operation).  It would be cool if I could write:

Eigen::ArrayXi values_i_want;
// Indices values_i_want (e.g. 0, 2, 3)

Eigen::VectorXd all_my_values;
// Values of global vector (0.0, 1.1, 2.2, 3.3, 4.4, ...)

Eigen::VectorXd values_i_have = all_my_values(values_i_want);
// values_i_have (0.0, 2.2, 3.3)

I think Matlab does something similar.

Would this be possible?  It could take advantage of some newer SIMD gather instructions on newer Intel CPUs if they are any good (I haven't tried them yet though).
Comment 1 Gael Guennebaud 2016-10-25 20:30:32 UTC

*** This bug has been marked as a duplicate of bug 329 ***
Comment 2 Nobody 2019-12-04 16:28:05 UTC
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