Eigenvector result is unusual

[Rich]

Hi,

When i type in

EIGENVV([1,2],[4,3])

I get this result:

{[[0.4472135955,−0.7453559925],[0.894427191,0.7453559925]],[[5.,0],[0,-1.]]}

I am not sure if my math is wrong somewhere, but on paper i get the different eigenvalues, for 5, i get [1 2] and for -1, I get [1 -1] which is what wolfram alpha gets. My 50G gets a value of [.5 1] and [1 -1] for for 5 and -1 respectively. Which is also correct.

EDIT::: Actually looking a little past the abstract, the results are correct, but I am not sure why the HP Prime didn't come up with a number closer to a whole number or more readable output similar to the 50G.

[Helge Gabert]

I don't think the math is wrong.

The eigenvalues of lambda1 and lambda2 are correct (5, and -1), and this is also what Wolfram alpha shows.

The eigenvectors are [.44..., .89...], and multiplied by a suitable scaling factor equals [1,2], and ditto for the other eigenvector [-.74..., .74], which, again, multiplied with a suitable scaling factor equals [-1,1] - - again in agreement with Wolfram alpha. I believe you read the vectors the wrong way - - horizontally instead of vertically.

But we can ask - - why doesn't the Prime normalize the eigenvectors?

[Rich]

Thanks for the update, I was reading it wrong. I noticed that it when diagonalizing the matrix on the Prime, with those eigenvectors, it still gives me the correct result but instead of a zeros, it has -1.42109E-15, which is essentially zero... but maybe due to the original output.

[parisse]

EIGENVV is an approx instruction. Try an exact one, for example jordan.

[Rich]

Thank you, the Jordan function works perfectly.