Hulk did something

[bytom/vapor.git] / vendor / gonum.org / v1 / gonum / lapack / gonum / dtrti2.go

diff --git a/vendor/gonum.org/v1/gonum/lapack/gonum/dtrti2.go b/vendor/gonum.org/v1/gonum/lapack/gonum/dtrti2.go
new file mode 100644 (file)
index 0000000..a43efe6
--- /dev/null
+++ b/vendor/gonum.org/v1/gonum/lapack/gonum/dtrti2.go
@@ -0,0 +1,57 @@
+// Copyright ©2015 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gonum
+
+import (
+       "gonum.org/v1/gonum/blas"
+       "gonum.org/v1/gonum/blas/blas64"
+)
+
+// Dtrti2 computes the inverse of a triangular matrix, storing the result in place
+// into a. This is the BLAS level 2 version of the algorithm.
+//
+// Dtrti2 is an internal routine. It is exported for testing purposes.
+func (impl Implementation) Dtrti2(uplo blas.Uplo, diag blas.Diag, n int, a []float64, lda int) {
+       checkMatrix(n, n, a, lda)
+       if uplo != blas.Upper && uplo != blas.Lower {
+               panic(badUplo)
+       }
+       if diag != blas.NonUnit && diag != blas.Unit {
+               panic(badDiag)
+       }
+       bi := blas64.Implementation()
+
+       nonUnit := diag == blas.NonUnit
+       // TODO(btracey): Replace this with a row-major ordering.
+       if uplo == blas.Upper {
+               for j := 0; j < n; j++ {
+                       var ajj float64
+                       if nonUnit {
+                               ajj = 1 / a[j*lda+j]
+                               a[j*lda+j] = ajj
+                               ajj *= -1
+                       } else {
+                               ajj = -1
+                       }
+                       bi.Dtrmv(blas.Upper, blas.NoTrans, diag, j, a, lda, a[j:], lda)
+                       bi.Dscal(j, ajj, a[j:], lda)
+               }
+               return
+       }
+       for j := n - 1; j >= 0; j-- {
+               var ajj float64
+               if nonUnit {
+                       ajj = 1 / a[j*lda+j]
+                       a[j*lda+j] = ajj
+                       ajj *= -1
+               } else {
+                       ajj = -1
+               }
+               if j < n-1 {
+                       bi.Dtrmv(blas.Lower, blas.NoTrans, diag, n-j-1, a[(j+1)*lda+j+1:], lda, a[(j+1)*lda+j:], lda)
+                       bi.Dscal(n-j-1, ajj, a[(j+1)*lda+j:], lda)
+               }
+       }
+}