Skip to content

fix: indexing issue, make the representation of lastv consistent with LAPACK source in lapack/base/dlarf1f #13436

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
aayush0325 wants to merge 2 commits into
base: develop
Choose a base branch
from
+6 −5
Open

fix: indexing issue, make the representation of lastv consistent with LAPACK source in lapack/base/dlarf1f #13436

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
06ee33c
fix: indexing issue, make the representation of lastv consistent with…
aayush0325 Jul 12, 2026
1afb143
Apply suggestions from code review
kgryte Jul 12, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 6 additions & 5 deletions lib/node_modules/@stdlib/lapack/base/dlarf1f/lib/base.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -108,16 +108,17 @@ function dlarf1f( side, M, N, V, strideV, offsetV, tau, C, strideC1, strideC2, o
i = offsetV + ( ( lastv-1 ) * strideV );

// Move `i` to the last non-zero element in `V`, where we assume that V[0] = 1, and it is not stored, so we shouldn't access it...
while ( lastv > 0 && V[ i ] === 0.0 ) {
while ( lastv > 1 && V[ i ] === 0.0 ) { // `lastv` should be greater than 1 as it represents the last one-based index with a zero value
lastv -= 1;
i -= strideV;
}

if ( isLeftSide( side ) ) {
// Scan for the last non-zero column in `C`:
lastc = iladlc( lastv + 1, N, C, strideC1, strideC2, offsetC ) + 1; // adjust by `+1` to account for the difference between zero-based and one-based indexing
lastc = iladlc( lastv, N, C, strideC1, strideC2, offsetC ) + 1; // adjust by `+1` to account for the difference between zero-based and one-based indexing
} else {
// Scan for the last non-zero row in `C`:
lastc = iladlr( M, lastv + 1, C, strideC1, strideC2, offsetC ) + 1; // // adjust by `+1` to account for the difference between zero-based and one-based indexing
lastc = iladlr( M, lastv, C, strideC1, strideC2, offsetC ) + 1; // // adjust by `+1` to account for the difference between zero-based and one-based indexing
}
// Return `C` unchanged if all elements in `C` are zero...
if ( lastc === 0 ) {
Expand All @@ -127,7 +128,7 @@ function dlarf1f( side, M, N, V, strideV, offsetV, tau, C, strideC1, strideC2, o
// Form: H*C

// If `lastv = 1`, this means `V = 1`, so we just need to compute `C = H*C = (1-tau)*C`...
if ( lastv === 0 ) {
if ( lastv === 1 ) {
// C[0,0:lastc] = (1-tau)*C[0,0:lastc]
dscal( lastc, 1.0-tau, C, strideC2, offsetC ); // scale the first row
} else {
Expand All @@ -154,7 +155,7 @@ function dlarf1f( side, M, N, V, strideV, offsetV, tau, C, strideC1, strideC2, o
// Form: C*H

// If `N = 1`, then `V = 1`, so we just need to compute `C = CH = C*(1-tau)`...
if ( lastv === 0 ) {
if ( lastv === 1 ) {
// C[0:lastc,0] = ( 1-tau ) * C[0:lastc,0]
dscal( lastc, 1.0-tau, C, strideC1, offsetC ); // scale the first column
return C;
Expand Down