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cperm

  1. C CPERM     SOURCE    CHAT      05/01/12    22:26:04     5004
  2.       SUBROUTINE CPERM (NROW,A,JA,IA,AO,JAO,IAO,PERM,JOB)
  3.       IMPLICIT INTEGER(I-N)
  4.       IMPLICIT REAL*8 (A-H,O-Z)
  5. C***********************************************************************
  6. C NOM         : CPERM
  7. C DESCRIPTION : Permutation des colonnes d'une matrice Morse.
  8. C
  9. C
  10. C LANGAGE     : FORTRAN 77
  11. C ADAPTATION  :  Stéphane GOUNAND (CEA/DRN/DMT/SEMT/LTMF)
  12. C                mél : gounand@semt2.smts.cea.fr
  13. C AUTEUR      :
  14. C  Sparskit : a basic tool kit for sparse matrix computations
  15. C  Version 2 (Youcef Saad)
  16. C  -> URL : http://www.cs.umn.edu/Research/arpa/SPARSKIT/sparskit.html
  17. C
  18. C***********************************************************************
  19.       INTEGER NROW,JA(*),IA(NROW+1),JAO(*),IAO(NROW+1),PERM(*), JOB
  20.       REAL*8 A(*), AO(*)
  21. c-----------------------------------------------------------------------
  22. c this subroutine permutes the columns of a matrix a, ja, ia.
  23. c the result is written in the output matrix  ao, jao, iao.
  24. c cperm computes B = A P, where  P is a permutation matrix
  25. c that maps column j into column perm(j), i.e., on return
  26. c      a(i,j) becomes a(i,perm(j)) in new matrix
  27. c Y. Saad, May 2, 1990 / modified Jan. 28, 1991.
  28. c-----------------------------------------------------------------------
  29. c on entry:
  30. c----------
  31. c nrow  = row dimension of the matrix
  32. c
  33. c a, ja, ia = input matrix in csr format.
  34. c
  35. c perm  = integer array of length ncol (number of columns of A
  36. c         containing the permutation array  the columns:
  37. c         a(i,j) in the original matrix becomes a(i,perm(j))
  38. c         in the output matrix.
  39. c
  40. c job   = integer indicating the work to be done:
  41. c               job = 1 permute a, ja, ia into ao, jao, iao
  42. c                       (including the copying of real values ao and
  43. c                       the array iao).
  44. c               job .ne. 1 :  ignore real values ao and ignore iao.
  45. c
  46. c------------
  47. c on return:
  48. c------------
  49. c ao, jao, iao = input matrix in a, ja, ia format (array ao not needed)
  50. c
  51. c Notes:
  52. c-------
  53. c 1. if job=1 then ao, iao are not used.
  54. c 2. This routine is in place: ja, jao can be the same.
  55. c 3. If the matrix is initially sorted (by increasing column number)
  56. c    then ao,jao,iao  may not be on return.
  57. c
  58. c----------------------------------------------------------------------c
  59. c local parameters:
  60.       INTEGER K, I, NNZ
  61. c
  62.       NNZ = IA(NROW+1)-1
  63.       DO 100 K=1,NNZ
  64.          JAO(K) = PERM(JA(K))
  65.  100  CONTINUE
  66. c
  67. c     done with ja array. return if no need to touch values.
  68. c
  69.       IF (JOB .NE. 1) RETURN
  70. c
  71. c else get new pointers -- and copy values too.
  72. c
  73.       DO 1 I=1, NROW+1
  74.          IAO(I) = IA(I)
  75.  1    CONTINUE
  76. c
  77.       DO 2 K=1, NNZ
  78.          AO(K) = A(K)
  79.  2    CONTINUE
  80. c
  81.       RETURN
  82. c---------end-of-cperm--------------------------------------------------
  83. c-----------------------------------------------------------------------
  84.       END
  85.  
  86.  
  87.  

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