Issue 18204: Conv. 'kernel_size()' incorrect for symmetric kernels (vsiplxx-rtf)
Source:  (Mr. Brooks Moses, brooks.moses(at)dpdx.net)
Nature: Revision
Severity: Minor
Summary: Copied from an internal bug report:


PROBLEM: Convolution accessor 'kernel_size()' is defined to return the
domain having the same length for each dimension as 'filter_coeffs'.
However, when constructing a convolution with a symmetric kernel
(sym_even_len_odd or sym_even_len_even), 'filter_coeffs' only holds
a subset of coefficients.  In those cases, the true kernel size is
larder (For example, in 1D convolutions the true size will either '2 *
filter_coeffs.size()' or '2 * filter_coeff.size() + 1').


In contrast, the C-VSIPL spec defines the kernel size as M, and
specifies the size of 'filter_coeffs' as either M if symmetry =
non_sym, or 'floor(M/2)' if 'symmetry == sym_even_len_{odd,even}'.
Queries to return the kernel size of a convolution return M.


PROPOSED FIX: Change wording of 'kernel_size()' accessor (and
Convolution constructor effects) to indicate correct kernel size.


TODO: Review specification of Correlation, FIR, and IIR for similar
error.
Resolution: In the interest of closing the current RTF so that the solutions to resolved issues can be made publically available, this issue is deferred to the next RTF.
Disposition: Deferred
Revised Text: 
Actions taken:
October 23, 2012: received issue
Discussion: 

End of Annotations:=====
te: Tue, 23 Oct 2012 11:09:33 -0700
From: Brooks Moses <brooks_moses@mentor.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2
To: <issues@omg.org>
Subject: VSIPL++ issue (#10 from me)
X-OriginalArrivalTime: 23 Oct 2012 18:09:33.0372 (UTC) FILETIME=[8DD26FC0:01CDB149]


Name:            Brooks Moses
Employer:        Mentor Graphics
mailFrom:        brooks_moses@mentor.com
Terms_Agreement: I agree
Specification:   VSIPL++
Section:         13.4.3 [signal.convol.constructors]
FormalNumber:    ptc/2012-07-27
Version:         1.2 - FTF Beta 1
Doc_Year:        2012
Doc_Month:       August
Doc_Day:         10
Page:            211
Title:           Conv. 'kernel_size()' incorrect for symmetric kernels.
Nature:          Bug
Severity:        Minor
B1:              Report Issue


Description:


Copied from an internal bug report:


PROBLEM: Convolution accessor 'kernel_size()' is defined to return the
domain having the same length for each dimension as 'filter_coeffs'.
However, when constructing a convolution with a symmetric kernel
(sym_even_len_odd or sym_even_len_even), 'filter_coeffs' only holds
a subset of coefficients.  In those cases, the true kernel size is
larder (For example, in 1D convolutions the true size will either '2 *
filter_coeffs.size()' or '2 * filter_coeff.size() + 1').


In contrast, the C-VSIPL spec defines the kernel size as M, and
specifies the size of 'filter_coeffs' as either M if symmetry =
non_sym, or 'floor(M/2)' if 'symmetry == sym_even_len_{odd,even}'.
Queries to return the kernel size of a convolution return M.


PROPOSED FIX: Change wording of 'kernel_size()' accessor (and
Convolution constructor effects) to indicate correct kernel size.


TODO: Review specification of Correlation, FIR, and IIR for similar
error.