- #1

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The only way I know is to set up the matrix with the 4x4 matrix and the identity matrix and row reduce. But that takes forever sometimes.

- Thread starter pyroknife
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- #1

- 613

- 3

The only way I know is to set up the matrix with the 4x4 matrix and the identity matrix and row reduce. But that takes forever sometimes.

- #2

gabbagabbahey

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It is often (but not always) faster to use the determinant and the adjugate matrix.

The only way I know is to set up the matrix with the 4x4 matrix and the identity matrix and row reduce. But that takes forever sometimes.

- #3

Ray Vickson

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It is hardly ever faster to use determinants. You would need to calculate 16 determinants, each of which is 3x3, so each involves 9 three-factor multiplications, plus keeping track of signs and worrying about roundoff error effects. Direct row-reduction is likely much faster in the vast majority of cases. And, yes, it can involve a lot of work, but that's life!It is often (but not always) faster to use the determinant and the adjugate matrix.

RGV

- #4

HallsofIvy

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Personally, I've always felt that row-reducing was faster than finding the determinant.

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