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+--- Thread: Help with imaginary number output from CAS (/thread-1634.html)
Help with imaginary number output from CAS - Rich - 06-15-2014 11:35 PM
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.
[attachment=834]
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.
RE: Help with imaginary number output from CAS - Helge Gabert - 06-16-2014 03:00 AM
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].
RE: Help with imaginary number output from CAS - Nigel (UK) - 06-16-2014 09:31 AM
(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)
RE: Help with imaginary number output from CAS - Rich - 06-17-2014 06:32 AM
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).