lapack: imported lapack as a subtree

lapack/native/dlaswp.go

@@ -0,0 +1,47 @@
+// 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 native
+
+import "github.com/gonum/blas/blas64"
+
+// Dlaswp swaps the rows k1 to k2 of a rectangular matrix A according to the
+// indices in ipiv so that row k is swapped with ipiv[k].
+//
+// n is the number of columns of A and incX is the increment for ipiv. If incX
+// is 1, the swaps are applied from k1 to k2. If incX is -1, the swaps are
+// applied in reverse order from k2 to k1. For other values of incX Dlaswp will
+// panic. ipiv must have length k2+1, otherwise Dlaswp will panic.
+//
+// The indices k1, k2, and the elements of ipiv are zero-based.
+//
+// Dlaswp is an internal routine. It is exported for testing purposes.
+func (impl Implementation) Dlaswp(n int, a []float64, lda int, k1, k2 int, ipiv []int, incX int) {
+	switch {
+	case n < 0:
+		panic(nLT0)
+	case k2 < 0:
+		panic(badK2)
+	case k1 < 0 || k2 < k1:
+		panic(badK1)
+	case len(ipiv) != k2+1:
+		panic(badIpiv)
+	case incX != 1 && incX != -1:
+		panic(absIncNotOne)
+	}
+
+	if n == 0 {
+		return
+	}
+	bi := blas64.Implementation()
+	if incX == 1 {
+		for k := k1; k <= k2; k++ {
+			bi.Dswap(n, a[k*lda:], 1, a[ipiv[k]*lda:], 1)
+		}
+		return
+	}
+	for k := k2; k >= k1; k-- {
+		bi.Dswap(n, a[k*lda:], 1, a[ipiv[k]*lda:], 1)
+	}
+}