(systemds) branch main updated: [MINOR] Performance improvement of dist

[baunsgaard]

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The following commit(s) were added to refs/heads/main by this push:
     new d01c61d7d5 [MINOR] Performance improvement of dist
d01c61d7d5 is described below

commit d01c61d7d56f250223f60fff6e773ba0870a7bee
Author: ramesesz <ramawidyadhanabhagask...@gmail.com>
AuthorDate: Mon Dec 11 16:43:13 2023 +0100

    [MINOR] Performance improvement of dist
    
    This patch improves the builtin dist function
    by removing the outer product operator. For 100
    function calls on an arbitrary matrix with 4000
    rows and 800 cols, the new dist function shortens
    the runtime from 66.541s to 60.268s.
    
    Closes #1959
---
 scripts/builtin/dist.dml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/scripts/builtin/dist.dml b/scripts/builtin/dist.dml
index 26ded9a197..f296fd717b 100644
--- a/scripts/builtin/dist.dml
+++ b/scripts/builtin/dist.dml
@@ -32,7 +32,8 @@
 # 
-----------------------------------------------------------------------------------------------
 
 m_dist = function(Matrix[Double] X) return (Matrix[Double] Y) {
-  G = X %*% t(X);
-  Y = sqrt(-2 * G + outer(diag(G), t(diag(G)), "+"));
+  n = nrow(X)
+  s = rowSums(X^2)
+  Y = sqrt(-2 * X %*% t(X) + s + t(s))
   Y = replace(target = Y, pattern=NaN, replacement = 0);
 }