From 162472b11b5b6e9de3b79e70facb3a61a6f61d40 Mon Sep 17 00:00:00 2001
From: Vladimir Chalupecky <vladimir@chalupecky.dev>
Date: Mon, 28 Sep 2020 11:09:24 +0200
Subject: [PATCH] lapack64: add Tbtrs

---
 lapack/lapack.go            |  1 +
 lapack/lapack64/lapack64.go | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/lapack/lapack.go b/lapack/lapack.go
index da0e670b..947cbe45 100644
--- a/lapack/lapack.go
+++ b/lapack/lapack.go
@@ -35,6 +35,7 @@ type Float64 interface {
 	Dpotri(ul blas.Uplo, n int, a []float64, lda int) (ok bool)
 	Dpotrs(ul blas.Uplo, n, nrhs int, a []float64, lda int, b []float64, ldb int)
 	Dsyev(jobz EVJob, uplo blas.Uplo, n int, a []float64, lda int, w, work []float64, lwork int) (ok bool)
+	Dtbtrs(uplo blas.Uplo, trans blas.Transpose, diag blas.Diag, n, kd, nrhs int, a []float64, lda int, b []float64, ldb int) (ok bool)
 	Dtrcon(norm MatrixNorm, uplo blas.Uplo, diag blas.Diag, n int, a []float64, lda int, work []float64, iwork []int) float64
 	Dtrtri(uplo blas.Uplo, diag blas.Diag, n int, a []float64, lda int) (ok bool)
 	Dtrtrs(uplo blas.Uplo, trans blas.Transpose, diag blas.Diag, n, nrhs int, a []float64, lda int, b []float64, ldb int) (ok bool)
diff --git a/lapack/lapack64/lapack64.go b/lapack/lapack64/lapack64.go
index a0c5f3c6..ec9a6f78 100644
--- a/lapack/lapack64/lapack64.go
+++ b/lapack/lapack64/lapack64.go
@@ -559,6 +559,17 @@ func Syev(jobz lapack.EVJob, a blas64.Symmetric, w, work []float64, lwork int) (
 	return lapack64.Dsyev(jobz, a.Uplo, a.N, a.Data, max(1, a.Stride), w, work, lwork)
 }
 
+// Tbtrs solves a triangular system of the form
+//  A * X = B   if trans == blas.NoTrans
+//  Aᵀ * X = B  if trans == blas.Trans or blas.ConjTrans
+// where A is an n×n triangular band matrix, and B is an n×nrhs matrix.
+//
+// Tbtrs returns whether A is non-singular. If A is singular, no solutions X
+// are computed.
+func Tbtrs(trans blas.Transpose, a blas64.TriangularBand, b blas64.General) (ok bool) {
+	return lapack64.Dtbtrs(a.Uplo, trans, a.Diag, a.N, a.K, b.Cols, a.Data, max(1, a.Stride), b.Data, max(1, b.Stride))
+}
+
 // Trcon estimates the reciprocal of the condition number of a triangular matrix A.
 // The condition number computed may be based on the 1-norm or the ∞-norm.
 //