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