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34 lines
818 B
Go
34 lines
818 B
Go
// Copyright ©2015 The gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package native
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// Iladlc scans a matrix for its last non-zero column. Returns -1 if the matrix
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// is all zeros.
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//
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// Iladlc is an internal routine. It is exported for testing purposes.
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func (Implementation) Iladlc(m, n int, a []float64, lda int) int {
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if n == 0 || m == 0 {
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return n - 1
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}
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checkMatrix(m, n, a, lda)
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// Test common case where corner is non-zero.
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if a[n-1] != 0 || a[(m-1)*lda+(n-1)] != 0 {
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return n - 1
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}
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// Scan each row tracking the highest column seen.
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highest := -1
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for i := 0; i < m; i++ {
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for j := n - 1; j >= 0; j-- {
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if a[i*lda+j] != 0 {
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highest = max(highest, j)
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break
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}
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}
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}
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return highest
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}
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