Weird result with Matrix determinant

03172015, 11:29 PM
Post: #3




RE: Weird result with Matrix determinant
(03172015 08:16 PM)Tugdual Wrote: Using Standard number format, Well, like any other device with limited working precision (12 resp. 15 digits internally) your calculator will cause a more or less significant roundoff error with every single operation. Evaluating the determinant of a matrix with numerical methods, i.e. not by Cramer's rule or similar exact solutions that are not suitable for larger matrices, usually is done via the wellknown Gauss algorithm resp. a LUdecomposition, leaving the product of the diagonal elements as the desired result. All this involves dozens, if not hundreds of multiplications, divisions and additions. Try a simple example like 2/3 – 2*(1/3) and you'll see how limited the accuracy of even a closetoperfect calculator can be. A tiny error in the least significant digit is a very good result here. With other matrices the error can grow much, much larger. Dieter 

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Messages In This Thread 
Weird result with Matrix determinant  Tugdual  03172015, 08:16 PM
RE: Weird result with Matrix determinant  Damien  03172015, 10:09 PM
RE: Weird result with Matrix determinant  Dieter  03172015 11:29 PM
RE: Weird result with Matrix determinant  Tugdual  03182015, 08:47 PM

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