Question: MatrixInverse makes rough approximations.


I'm dealing with a symmetric matrix with numerical values, very high values, e.g. 10^(50), let's call it low_index

Maple computed the inverse with

up_index:= MatrixInverse(low_index);


and then, if I compute the product of the two (with should be the identity) I get

  [0.,1.00000024,-4. 10^(-10),-4. 10^(-9),-0.0004],
  [0.,0.000001,1. 10^(-8),1.0000001,-0.04],
  [0.,3. 10^(-11),-1.0 10^(-13),-1. 10^(-12),0.9999999]]]


So, I get off-diagonal values far from zero ( the [3,5] element for exemple)

This was done with Digits:=10;


It there a way to improve the precision of the inverse without raising the vaule of Digits (which makes my program to runs far too slowly)?




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