HP PRIME solves a equation wrongly

[Albert Chan]

(05-08-2023 02:00 PM)Arno K Wrote:  you may use csolve(equation,x,x>0), that calculates 2492.85983787.

Last argument, x>0, is not the reason for getting correct answer.
Besides, for complex number, x>0 is meaningless.

There is a bug, equation does not properly converted to numerical.
We can explicitly turn equation numerical.

Cas> m := approx(
(x+400)*0.8/(π*0.04^4/32) =
0.4*((x+400)*0.8/(π*0.04^4/32)+x*0.5/(0.141*(20*√2)^4*10^-12)))

(3183098.86184*(x+400.)) = (0.4*(3183098.86184*(x+400.)+5540780.14184*x))

Cas> solve(m)      → {2492.85983787}
Cas> csolve(m)     → {2492.85983787}
Cas> zeros(m)      → [2492.85983787]