Continuing on from: http://mail-archives.apache.org/mod_mbox/incubator-madlib-user/201702.mbox/%3CCAAKWcNHoxdVdEjRsAOjC9Zukjo2e5cLBP2XPFFC6f8XiXSMykA%40mail.gmail.com%3E
and https://issues.apache.org/jira/projects/MADLIB/issues/MADLIB-1067?filter=allopenissues Cosine similiarity is currently faster than array_dot, because it uses Eigen rather than a native implementation. I was looking at how hard it might be to change array_dot to use eigen as well. I can see that array_dot takes arguments of anyarray and returns float, whilst the eigen-based methods take DOUBLE PRECISION[] and return DOUBLE PRECISION. Does this mean the method cannot be safely replaced without breaking backward compatability? Maybe I could add a function called fast_array_dot, though that seems a bit messy? Or if the function can be outright replaced, I noticed that the eigen functions are declared in src/ports/postgres/modules/linalg/linalg.sql_in whilst the native array functions are declared in methods/array_ops/src/pg_gp/array_ops.sql_in, so in that case should the declaration be moved? -- James
