From b091b0b4e25267df4e0e5a4e9effe8b8ae992bee Mon Sep 17 00:00:00 2001
From: Vladimir Chalupecky <vladimir@chalupecky.dev>
Date: Fri, 4 Feb 2022 08:52:23 +0100
Subject: [PATCH] lapack/gonum: clarify ok return from Dpstrf and Dpstf2

---
 lapack/gonum/dpstf2.go      | 7 ++++---
 lapack/gonum/dpstrf.go      | 7 ++++---
 lapack/lapack64/lapack64.go | 7 ++++---
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/lapack/gonum/dpstf2.go b/lapack/gonum/dpstf2.go
index a1d10f94..134fa674 100644
--- a/lapack/gonum/dpstf2.go
+++ b/lapack/gonum/dpstf2.go
@@ -27,9 +27,10 @@ import (
 // On return, A contains the factor U or L from the Cholesky factorization and
 // piv contains P stored such that P[piv[k],k] = 1.
 //
-// Dpstf2 returns the computed rank of A and whether the algorithm completed
-// successfully. If ok is false, the matrix A is either rank deficient or is not
-// positive semidefinite.
+// Dpstf2 returns the computed rank of A and whether the factorization can be
+// used to solve a system. Dpstf2 does not attempt to check that A is positive
+// semi-definite, so if ok is false, the matrix A is either rank deficient or is
+// not positive semidefinite.
 //
 // The length of piv must be n and the length of work must be at least 2*n,
 // otherwise Dpstf2 will panic.
diff --git a/lapack/gonum/dpstrf.go b/lapack/gonum/dpstrf.go
index 5c591a2a..21ea49a3 100644
--- a/lapack/gonum/dpstrf.go
+++ b/lapack/gonum/dpstrf.go
@@ -27,9 +27,10 @@ import (
 // On return, A contains the factor U or L from the Cholesky factorization and
 // piv contains P stored such that P[piv[k],k] = 1.
 //
-// Dpstrf returns the computed rank of A and whether the algorithm completed
-// successfully. If ok is false, the matrix A is either rank deficient or is not
-// positive semidefinite.
+// Dpstrf returns the computed rank of A and whether the factorization can be
+// used to solve a system. Dpstrf does not attempt to check that A is positive
+// semi-definite, so if ok is false, the matrix A is either rank deficient or is
+// not positive semidefinite.
 //
 // The length of piv must be n and the length of work must be at least 2*n,
 // otherwise Dpstrf will panic.
diff --git a/lapack/lapack64/lapack64.go b/lapack/lapack64/lapack64.go
index 9e5f1546..66bbd9d0 100644
--- a/lapack/lapack64/lapack64.go
+++ b/lapack/lapack64/lapack64.go
@@ -145,9 +145,10 @@ func Pbtrs(t blas64.TriangularBand, b blas64.General) {
 // and the underlying data between a and t is shared. P is stored on return in
 // vector piv such that P[piv[k],k] = 1.
 //
-// Pstrf also returns the computed rank of A and whether the algorithm completed
-// successfully. If ok is false, the matrix A is either rank deficient or is not
-// positive semidefinite.
+// Pstrf returns the computed rank of A and whether the factorization can be
+// used to solve a system. Pstrf does not attempt to check that A is positive
+// semi-definite, so if ok is false, the matrix A is either rank deficient or is
+// not positive semidefinite.
 //
 // The length of piv must be n and the length of work must be at least 2*n,
 // otherwise Pstrf will panic.