!standard G.3.1(1) 05-03-09 AI95-00418-01/01
!standard G.3.2(1)
!class amendment 05-03-09
!status work item 05-03-09
!status received 05-03-09
!priority High
!difficulty Easy
!subject Vector norm
!summary
(See proposal.)
!problem
While the packages Generic_Real_Arrays and Generic_Complex_Arrays provide inner
product, they do not provide a related operation that is often used in
practice, the norm. Normalizing a vector is common and it seems unfriendly to
require the user to implement the norm based on the inner product (and
conjugation), especially as intermediate overflows/underflows could occur.
!proposal
Add "abs" operators implementing the L2-norm.
[What the heck is an L2-norm? We can't have terms that poorly defined in the
standard. - ED]
!wording
Add after G.3.1(9):
function "abs" (Right : Real_Vector) return Real'Base;
Add after G.3.1(39):
function "abs" (Right : Real_Vector) return Real'Base;
This operation returns the L2-norm of Right. This operation involves an inner
product.
Add after G.3.2(15):
function "abs" (Right : Complex_Vector) return Real'Base;
Add after G.3.2(73):
function "abs" (Right : Complex_Vector) return Real'Base;
This operation returns the Hermitian L2-norm of Right. This operation involves
an inner product.
!discussion
(See proposal.)
!example
--!corrigendum
!ACATS test
Test cases should be added to the ACATS tests created for AI-296.
!appendix
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