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RE: AI-GEOSTATS: singular matrix during conditional simulation

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  • Rajive Ganguli, Ph.D.
    I do not anything about GSLIB, but when two rows or cols in a matrix are identical, the determinant of the matrix is zero. A matrix is called singular when its
    Message 1 of 2 , Jul 15, 2003
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      I do not anything about GSLIB, but when two rows or cols in a matrix are
      identical, the determinant of the matrix is zero. A matrix is called
      singular when its det. is zero. A singular matrix cannot be inverted.

      Note that it is also possible for the product of two matrices to have a zero
      determinant, without each of them being zero.


      Rajive Ganguli, Ph.D., P.E., C.O.I
      Associate Professor of Mining Engineering
      University of Alaska Fairbanks
      =====
      Office: 317 Duckering Building
      Mailing Add: Box 755800, Fairbanks, AK 99775
      ph: 907-474-7631, fax: 907-474-6635
      web: http://www.faculty.uaf.edu/ffrg/




      > -----Original Message-----
      > From: ai-geostats-list@... [mailto:ai-geostats-list@...]On
      > Behalf Of Ulrich Leopold
      > Sent: Tuesday, July 15, 2003 3:25 AM
      > To: ai-geostats@...
      > Subject: AI-GEOSTATS: singular matrix during conditional simulation
      >
      >
      > Dear list,
      >
      > I encounter a problem in Gstat. I posted my message to the
      > Gstat list but get currently no answer.
      > Maybe someone here experienced this problem already in Gstat
      > or has any ideas how to solve it:
      >
      > Gstat terminates with the message "matrix library error: singular
      > matrix" (see below). The trouble shooting in the manual says:
      > Increase the value of zero.
      > I did that. Nothing changes. Another solution is to average
      > values at identical locations.
      > I did that as well with the average option in data().
      >
      > I had a look to the debug file but do not quite get a clue
      > from it except that the last matrix
      > has 2 identical columns?? That's when Gstat stops. You can
      > find that matrix below as well.
      > Any ideas how to solve this problem?
      >
      > Ulrich
      >
      > ---------------------------------------------------------------
      >
      > gstat: Linux version 2.4.2 (26 April 2003)
      > Copyright (C) 1992, 2003 Edzer J. Pebesma
      > using Marsaglia's random number generator
      >
      > [using conditional gaussian simulation]
      > initializing maps .
      > 0% done
      > "chfactor.c", line 130: singular matrix in function LDLfactor()
      >
      > gstat caught an error that occurred in the matrix library,
      > the reason for it was: singular matrix
      >
      > HINT: Read the manual (http://www.geog.uu.nl/gstat/manual)
      > look for: Trouble shooting -> Error messages -> From meschach
      >
      > gstat: matrix library error: singular matrix
      >
      > --------------------------------------------------------------------
      >
      > idx x:;y:;z:;v:;
      > 0 x: 254083 y: 552263 z: 0 weight: 1
      >
      > # Covariances (x_i, x_j) matrix C (lower triangle only):
      > Matrix: 10 by 10
      > row 0: 174.0506 0 0 0
      > 0 0 0 0
      > 0
      > 0
      > row 1: 174.0506 174.0506 0 0
      > 0 0 0 0
      > 0
      > 0
      > row 2: 45.0007921 45.0007921 174.0506 0
      > 0 0 0 0
      > 0
      > 0
      > row 3: 43.8068348 43.8068348 37.2124655 174.0506
      > 0 0 0 0
      > 0
      > 0
      > row 4: 43.4219499 43.4219499 36.9949687 52.578787
      > 174.0506 0 0 0
      > 0
      > 0
      > row 5: 40.3552653 40.3552653 36.7606584 43.6115366
      > 44.1867844 52.612507 0 0
      > 0
      > 0
      > row 6: 38.927339 38.927339 42.9203931 34.49808
      > 34.5784392 38.2033244 52.612507 0
      > 0
      > 0
      > row 7: 45.4024655 45.4024655 38.5251957 45.9125721
      > 45.1916088 38.2033244 33.2536242 52.612507
      > 0
      > 0
      > row 8: 43.4915577 43.4915577 36.7949906 52.0550197
      > 51.3836065 42.5157124 33.7749338 46.6269808
      > 174.0506
      > 0
      > row 9: 40.7441753 40.7441753 48.2783442 33.6299795
      > 33.4342596 33.6128998 42.2386301 35.0813766
      > 33.260144
      > 174.0506
      >
      > --------------------------------------------------------------
      > ---------------
      >
      >
      > --
      > __________________________________________________
      >
      > Ulrich Leopold MSc.
      >
      > Department of Physical Geography
      > Institute for Biodiversity and Ecosystem Dynamics
      > Faculty of Science
      > University of Amsterdam
      > Nieuwe Achtergracht 166
      > NL-1018WV Amsterdam
      >
      > Phone: +31-(0)20-525-7456 (7451 Secretary)
      > Fax: +31-(0)20-525-7431
      > Email: uleopold@...
      > http://www.frw.uva.nl/soil/Welcome.html
      >
      > Check us also out at:
      > Netherlands Centre for Geo-ecological Research
      > http://www.frw.uva.nl/icg
      >
      >
      >
      >
      >
      > --
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