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AI-GEOSTATS: SUM: Border effect

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  • Gregoire Dubois
    In addition to Pierre s comments on the risks of extrapolating, I also got the two following replies Lynn J. Torak Perhaps the border effect is caused by an
    Message 1 of 1 , Mar 24, 2003
      In addition to Pierre's comments on the risks of extrapolating, I also got the
      two following replies

      Lynn J. Torak

      "Perhaps the "border effect" is caused by an ill-conditioned matrix
      presented to either the direct or iterative solver of the geostat program,
      causing an oscillation in the solution."


      Dan W. McCarn

      "Just a thought, but perhaps the solution matrix is getting more and more
      "ill-conditioned" away from the center of the data set resulting in "unstable"
      solutions when the precision of the computer is marginal (say 32-bit
      floating-point numbers). I know that in one benchmark data set that I used,
      the results were up to 20% off the "true" values calculated at 64-bit and
      128-bit precision. This resulted in negative numbers where there should have
      been none"


      Thanks a lot to all for the kind support.

      Best regards,

      Gregoire


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