Some Wrong When Doing Matrix Inverse

[rtoy]

Imported from SourceForge on 2024-07-09 19:42:11
Created by luca010 on 2021-10-15 15:49:39
Original: https://sourceforge.net/p/maxima/bugs/3878

---

A:matrix(
[1/sqrt(2),-1/(3sqrt(2)),2/3],
[1/sqrt(2),1/(3sqrt(2)),-2/3],
[0,4/(3*sqrt(2)),1/3]
);
B:invert(A);

I got：
matrix(
[(2^(5/2)/9+1/(9sqrt(2)))/((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2), (2^(5/2)/9+1/(9sqrt(2)))/((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2), 0],
[-1/(3sqrt(2)((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2)), 1/(3sqrt(2)((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2)), 2^(3/2)/(3*((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2))],
[2/(3((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2)), -2/(3((2^(5/2)/9+1/(9sqrt(2)))/sqrt(2)+1/2)), 1/(3((2^(5/2)/9+1/(9*sqrt(2)))/sqrt(2)+1/2))]
)
That' wrong!

Attachments:

• https://sourceforge.net/p/maxima/bugs/3878/attachment/SharedScreenshot.jpg

[rtoy]

Imported from SourceForge on 2024-07-09 19:42:13
Created by macrakis on 2021-10-15 16:18:44
Original: https://sourceforge.net/p/maxima/bugs/3878/#4b05

---

The result is correct, though unsimplified. This behavior is documented:

'invert' does not apply any simplifications to the elements of the
inverse apart from the default arithmetic simplifications.
'ratsimp' and 'expand' can apply additional simplifications.

You can simplify it into a more familar form using ratsimp, expand, factor, etc.

[rtoy]

Imported from SourceForge on 2024-07-09 19:42:16
Created by macrakis on 2021-10-15 16:19:04
Original: https://sourceforge.net/p/maxima/bugs/3878/#141a

---

• status: open --> not-a-bug