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symmetric_matrix_rank_k_update != dsyrk #272
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Hi! Last week was a short week, so I didn't have a chance to take a look. I'll try to do that as soon as I can. Thanks! |
PR #275 looks like it fixes this -- thanks! : - ) |
Given the state of affairs rasolca@ discovered, there is just one doubt left: is the fact that dsyrk takes two scalars, but symmetric_matrix_rank_k_update takes one scalar (no beta) intentional (because one can easily premultiply C), or an oversight? |
@prlw1 It's probably an oversight, based on |
@prlw1 I've filed ORNL/cpp-proposals-pub#468 to track the |
As mentioned at the end of #261, I tried the example posted by @yigiter in #261 (comment)_ which lead me to wonder what
symmetric_matrix_rank_k_update
is computing.Given its name, I assume that
symmetric_matrix_rank_k_update
maps to the BLAS functiondsyrk
(but with a single scalar constant alpha, rather than BLAS's alpha and beta) described as:I reused @yigiter's example as follows:
which generates the output:
I expect the answer
as per the blas function (upper triangle).
Given some matrix
A
,A A^T
is going to be symmetric, so the symmetric constraint needs to be on the additive matrixC
in order to avoid a triangle of computations, The comment instdBLAS/include/experimental/__p1673_bits/blas3_matrix_rank_k_update.hpp
Line 152 in 06e90a5
A
is the matrix which needs to be symmetric?I am puzzled as to what
symmetric_matrix_rank_k_update
is meant to be computing?The text was updated successfully, but these errors were encountered: