Line data    Source code

       1             : //------------------------------------------------------------------------------
       2             : // LAGraph_Matrix_Structure: return the structure of a matrix
       3             : //------------------------------------------------------------------------------
       4             : 
       5             : // LAGraph, (c) 2019-2022 by The LAGraph Contributors, All Rights Reserved.
       6             : // SPDX-License-Identifier: BSD-2-Clause
       7             : //
       8             : // For additional details (including references to third party source code and
       9             : // other files) see the LICENSE file or contact permission@sei.cmu.edu. See
      10             : // Contributors.txt for a full list of contributors. Created, in part, with
      11             : // funding and support from the U.S. Government (see Acknowledgments.txt file).
      12             : // DM22-0790
      13             : 
      14             : // Contributed by Timothy A. Davis and Scott Kolodziej, Texas A&M University
      15             : 
      16             : //------------------------------------------------------------------------------
      17             : 
      18             : // LAGraph_Matrix_Structure: return the structure of a matrix as a boolean
      19             : // matrix, where C(i,j)=true if the entry A(i,j) is present in the matrix A.
      20             : 
      21             : #define LG_FREE_ALL GrB_free (C) ;
      22             : 
      23             : #include "LG_internal.h"
      24             : 
      25         563 : int LAGraph_Matrix_Structure
      26             : (
      27             :     // output:
      28             :     GrB_Matrix *C,  // a boolean matrix with same structure of A, with C(i,j)
      29             :                     // set to true if A(i,j) appears in the sparsity structure
      30             :                     // of A.
      31             :     // input:
      32             :     GrB_Matrix A,
      33             :     char *msg
      34             : )
      35             : {
      36             : 
      37             :     //--------------------------------------------------------------------------
      38             :     // check inputs
      39             :     //--------------------------------------------------------------------------
      40             : 
      41         563 :     LG_CLEAR_MSG ;
      42             :     GrB_Index nrows, ncols ;
      43         563 :     LG_ASSERT_MSG (C != NULL, GrB_NULL_POINTER, "&C != NULL") ;
      44         562 :     LG_ASSERT (A != NULL, GrB_NULL_POINTER) ;
      45         561 :     (*C) = NULL ;
      46             : 
      47             :     //--------------------------------------------------------------------------
      48             :     // get the size of A
      49             :     //--------------------------------------------------------------------------
      50             : 
      51         561 :     GRB_TRY (GrB_Matrix_nrows (&nrows, A)) ;
      52         561 :     GRB_TRY (GrB_Matrix_ncols (&ncols, A)) ;
      53             : 
      54             :     //--------------------------------------------------------------------------
      55             :     // C<s(A)> = true
      56             :     //--------------------------------------------------------------------------
      57             : 
      58         561 :     GRB_TRY (GrB_Matrix_new (C, GrB_BOOL, nrows, ncols)) ;
      59         537 :     GRB_TRY (GrB_assign (*C, A, NULL, (bool) true,
      60             :         GrB_ALL, nrows, GrB_ALL, nrows, GrB_DESC_S)) ;
      61             : 
      62         512 :     return (GrB_SUCCESS) ;
      63             : }