github.com/gonum/lapack@v0.0.0-20181123203213-e4cdc5a0bff9/native/dlaset.go (about)

     1  // Copyright ©2015 The gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package native
     6  
     7  import "github.com/gonum/blas"
     8  
     9  // Dlaset sets the off-diagonal elements of A to alpha, and the diagonal
    10  // elements to beta. If uplo == blas.Upper, only the elements in the upper
    11  // triangular part are set. If uplo == blas.Lower, only the elements in the
    12  // lower triangular part are set. If uplo is otherwise, all of the elements of A
    13  // are set.
    14  //
    15  // Dlaset is an internal routine. It is exported for testing purposes.
    16  func (impl Implementation) Dlaset(uplo blas.Uplo, m, n int, alpha, beta float64, a []float64, lda int) {
    17  	checkMatrix(m, n, a, lda)
    18  	if uplo == blas.Upper {
    19  		for i := 0; i < m; i++ {
    20  			for j := i + 1; j < n; j++ {
    21  				a[i*lda+j] = alpha
    22  			}
    23  		}
    24  	} else if uplo == blas.Lower {
    25  		for i := 0; i < m; i++ {
    26  			for j := 0; j < min(i+1, n); j++ {
    27  				a[i*lda+j] = alpha
    28  			}
    29  		}
    30  	} else {
    31  		for i := 0; i < m; i++ {
    32  			for j := 0; j < n; j++ {
    33  				a[i*lda+j] = alpha
    34  			}
    35  		}
    36  	}
    37  	for i := 0; i < min(m, n); i++ {
    38  		a[i*lda+i] = beta
    39  	}
    40  }