Is it bug? CAS solve function.

[Tim Wessman]

Note that your numbers are correct as well!

0.000000000000000388578058619 is what it found.... which is basically 0

When solving using numerical methods, the computer changes the values by smaller and smaller amounts and attempts to converge onto a single number. However, it is very common that it can't "perfectly" find a number that works because computer numbers are not perfect! They have error built in, and algorithms can't be perfect in all situations. A human can look at a number and say "that should be 0" but that isn't always the case and a computer can't know it!

Much of the work in making good math libraries is figuring out how to reduce or cancel as much of the error as possible. For example, what is 1/3 ? Well, if you are using exact, CAS type systems then it is the "concept of 1 divided by 3" or a "ratio of 1 over 3". You CANNOT numerically represent .333333....... as it repeats infinitely however.

In this case, the generic "solve a number using a repetitive numerical calculation" algorithm in use can't perfectly converge down to 0. It does "almost" get there however.