[BUG?] Wrong numeric result with CAS `fsolve`/`zeros`/`solve`

[toml_12953]

(12-19-2016 04:15 AM)danielmewes Wrote:  I was reading this post in another forum http://forum.hp-prime.de/showthread.php?tid=183

and can confirm that all of the following result in the wrong root 0 on the Prime:
zeros(x^4 - 3x^3 - 2.75x^2 + 12x - 5)
solve(x^4 - 3x^3 - 2.75x^2 + 12x - 5 = 0)
fsolve(x^4 - 3x^3 - 2.75x^2 + 12x - 5 = 0)
-> [2.5, 2., -2., 0]

The correct result would be:
-> [2.5, 2., -2., 0.5]

Firmware version: 2016 08 29 (10637)

The same commands work correctly with giac 1.2.2.

Also, the exact version works on the Prime:
zeros(x^4 - 3x^3 - (275/100)*x^2 + 12x - 5)
-> [2, -2, 5/2, 1/2]


This looks more significant than a small rounding error.

On the Windows Virtual Calculator (build 11226), it's weird but the second function (solve) gets it right but the first and third get it wrong, as you have noted.

Tom L