Help with imaginary number output from CAS

[Rich]

Hi, when "complex" option in the CAS settings is checked, I am getting a "_x" in the output. Is this the correct result and should interpret this as something significant?

I think this was seen in an another error earlier but I am unsure if this is what should be expect when having this setting checked.

   

I have attached a screenshot that has both results, the first with the "complex" checked and the second with it off.

Thanks if anyone knows the answer.

[Helge Gabert]

I have noticed that same "_x" returned with a couple of expressions to be solved as well.

While I don't know why it shows up (maybe someone from the HP team knows more), what helped me in those cases was to specify an interval for the solver (e.g., x=-2 .. 2 instead of just x), which returns the solution [-1 1] without any problems (with "complex" checked).

[edit: in your case that would be w = -2 . . 2].

[Nigel (UK)]

(06-15-2014 11:35 PM)Rich Wrote:  Hi, when "complex" option in the CAS settings is checked, I am getting a "_x" in the output. Is this the correct result and should interpret this as something significant?

I think this was seen in an another error earlier but I am unsure if this is what should be expect when having this setting checked.



I have attached a screenshot that has both results, the first with the "complex" checked and the second with it off.

Thanks if anyone knows the answer.

My guess: _x is a free real variable. In other words, for any real value of _x there are two roots for w, given by those two complex expressions.

Nigel (UK)

[Rich]

Thank you, I was able to complete my function with the suggestion of a very wide interval, though I later returned and just made an assumption that w was in the domain of a real integer.

For any future reference, this was the command assume(w, DOM_INT).