lapack: imported lapack as a subtree

lapack/native/dlascl.go

@@ -0,0 +1,89 @@
+// 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 (
+	"math"
+
+	"github.com/gonum/lapack"
+)
+
+// Dlascl multiplies an m×n matrix by the scalar cto/cfrom.
+//
+// cfrom must not be zero, and cto and cfrom must not be NaN, otherwise Dlascl
+// will panic.
+//
+// Dlascl is an internal routine. It is exported for testing purposes.
+func (impl Implementation) Dlascl(kind lapack.MatrixType, kl, ku int, cfrom, cto float64, m, n int, a []float64, lda int) {
+	checkMatrix(m, n, a, lda)
+	if cfrom == 0 {
+		panic(zeroDiv)
+	}
+	if math.IsNaN(cfrom) || math.IsNaN(cto) {
+		panic(nanScale)
+	}
+	if n == 0 || m == 0 {
+		return
+	}
+	smlnum := dlamchS
+	bignum := 1 / smlnum
+	cfromc := cfrom
+	ctoc := cto
+	cfrom1 := cfromc * smlnum
+	for {
+		var done bool
+		var mul, ctol float64
+		if cfrom1 == cfromc {
+			// cfromc is inf.
+			mul = ctoc / cfromc
+			done = true
+			ctol = ctoc
+		} else {
+			ctol = ctoc / bignum
+			if ctol == ctoc {
+				// ctoc is either 0 or inf.
+				mul = ctoc
+				done = true
+				cfromc = 1
+			} else if math.Abs(cfrom1) > math.Abs(ctoc) && ctoc != 0 {
+				mul = smlnum
+				done = false
+				cfromc = cfrom1
+			} else if math.Abs(ctol) > math.Abs(cfromc) {
+				mul = bignum
+				done = false
+				ctoc = ctol
+			} else {
+				mul = ctoc / cfromc
+				done = true
+			}
+		}
+		switch kind {
+		default:
+			panic("lapack: not implemented")
+		case lapack.General:
+			for i := 0; i < m; i++ {
+				for j := 0; j < n; j++ {
+					a[i*lda+j] = a[i*lda+j] * mul
+				}
+			}
+		case lapack.UpperTri:
+			for i := 0; i < m; i++ {
+				for j := i; j < n; j++ {
+					a[i*lda+j] = a[i*lda+j] * mul
+				}
+			}
+		case lapack.LowerTri:
+			for i := 0; i < m; i++ {
+				for j := 0; j <= min(i, n-1); j++ {
+					a[i*lda+j] = a[i*lda+j] * mul
+				}
+			}
+		}
+		if done {
+			break
+		}
+	}
+}