0
$\begingroup$

I have a matrix where some entries are complex or roots of unity. For example,

(-1)^(2/9) - (-1)^(5/9) + (-1)^(8/9)

is one such entry and it is equal to 0.

When I send such an entry to Wolfram|Alpha, it gives me zero. But I have matrix full of such identities, so I want to do the simplification on the whole matrix and inside Mathematica.

Is there is anyway I can do that?

$\endgroup$
4
$\begingroup$

Here's a few approaches:

FullSimplify[(-1)^(2/9) - (-1)^(5/9) + (-1)^(8/9)]
0
Simplify[ExpToTrig[(-1)^(2/9) - (-1)^(5/9) + (-1)^(8/9)]]
0
PossibleZeroQ[(-1)^(2/9) - (-1)^(5/9) + (-1)^(8/9)]
True
$\endgroup$
3
  • $\begingroup$ so FullySimplify work for Matrix too? thanks $\endgroup$ – henry Feb 1 '19 at 1:26
  • 1
    $\begingroup$ It threads over lists, yes. $\endgroup$ – Chip Hurst Feb 1 '19 at 1:27
  • $\begingroup$ I tried it.. and its work.. thanks. $\endgroup$ – henry Feb 1 '19 at 1:28
2
$\begingroup$
      Simplify[ComplexExpand[(-1)^(2/9) - (-1)^(5/9) + (-1)^(8/9)]]
 (*  0  *) 
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.