lapack: imported lapack as a subtree

lapack/native/iladlr.go

@@ -0,0 +1,30 @@
+// 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
+
+// Iladlr scans a matrix for its last non-zero row. Returns -1 if the matrix
+// is all zeros.
+//
+// Iladlr is an internal routine. It is exported for testing purposes.
+func (Implementation) Iladlr(m, n int, a []float64, lda int) int {
+	if m == 0 {
+		return m - 1
+	}
+
+	checkMatrix(m, n, a, lda)
+
+	// Check the common case where the corner is non-zero
+	if a[(m-1)*lda] != 0 || a[(m-1)*lda+n-1] != 0 {
+		return m - 1
+	}
+	for i := m - 1; i >= 0; i-- {
+		for j := 0; j < n; j++ {
+			if a[i*lda+j] != 0 {
+				return i
+			}
+		}
+	}
+	return -1
+}