lapack/gonum: clarify ok return from Dpstrf and Dpstf2
MODIFY
lapack/gonum/dpstf2.go
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.

MODIFY
lapack/gonum/dpstrf.go
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.

MODIFY
lapack/lapack64/lapack64.go
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.

lapack/gonum: clarify ok return from Dpstrf and Dpstf2