Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077

05042016, 10:24 PM
(This post was last modified: 05042016 10:41 PM by Arno K.)
Post: #1




Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
Today I came across the task of getting a matrix simplified with different ways to perform, one was M= [[2,0,0,0],[2,2,0,0],[1,1,2,1],[0,1,0,2]], a Schur decomposition was to be done and this is provided by the Prime.
As I want to check out the Prime's capabilities I tried to get the eigenvalues, easily computed by hand, all are 2, the Prime gives a warning ( "Low accuracy" ) and using EIGENVAL(M3), provides 4 values which can be rounded to 2. Then I tried EIGENVV(M3) and the physical prime simply restarted, the PCemulator halted (both latest firmware) and the Androidapp (8151) crashed, too. Recalling M3 and EIGENVV(Ans) delivers: "Not invertible error: Bad Argument Value", contrary to Wolfram, saying [0,0,1,0] is an eigenvector and that is correct. Arno 

05052016, 05:08 AM
Post: #2




RE: Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
Crashed again because the Prime does not have exceptions, it returns a "not invertible error" on Xcas (this is expected because the matrix is not diagonalizable, therefore numeric diagonalization will fail while exact diagonalization works).


05062016, 06:32 PM
(This post was last modified: 05062016 06:32 PM by compsystems.)
Post: #3




RE: Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
MATHEMATICA
https://www.wolframalpha.com/input/?i=EI...0,2%5D%5D) [2,2,2] TI68K EIGVL([[2,0,0,0],[2,2,0,0],[1,1,2,1],[0,1,0,2]]) [enter] [2,2,2] hpprime EIGENVAL([[2,0,0,0],[2,2,0,0],[1,1,2,1],[0,1,0,2]]) [enter] "Low accuracy" then [2.00058131764,1.99961844696, 2.00018411644, 1.99961611895] https://www.wolframalpha.com/input/?i=EI...0,2%5D%5D) Prime does not have exceptions??? So, why not incorporated? 

05062016, 07:03 PM
Post: #4




RE: Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
You can get exact eigenvalues inside the CAS, even more jordan will return the Jordan normal form (not available on the ti).
Code: p,j:=jordan([[2,0,0,0],[2,2,0,0],[1,1,2,1],[0,1,0,2]]); p*j*inv(p); 

05062016, 09:21 PM
(This post was last modified: 05062016 10:51 PM by Arno K.)
Post: #5




RE: Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
Well, I did not (really) bother about the prime not being able to produce the eigenvectors, what I wanted to say is: it CRASHED using EIGENVV(M3) where M3 is one of the builtin matrices filled with the data provided above here the warning: Matrix is not diagonalizable, try.... would be a workaround.
Arno 

05072016, 06:51 AM
Post: #6




RE: Bug in EIGENVV in combination with builtin matrices M0..M9 in 10077
Of course it should not crash, it's now fixed in the source code.


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