I am using the HP Prime Virtual Calculator v2.1.14425 (2020 1 16) Parametric App to attempt to plot the continuous Fibonacci parametric function (image 1). It has a complex result and I am trying to plot the RE and IM parts. As T goes from -9 to 9 the resulting complex-valued result should look like the last image below, produced with Derive for Windows version 5.06. Instead, for example with Trace on and T = 1.5, I get the "(NaN, NaN)" result shown. But it is close -- Jump to T = 6 and the correct real value (8,0) is shown (the 6th Fibonacci sum 1 1 2 3 5 *8*).
Why isn't the desired plot shown by HP Prime?
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If you get the real and imaginary expressions from CAS and copy those to the parametric app, you get the desired result.
Do:
X1:=unnaply(RE(f(x)),x)
Y1:=unnaply(IM(f(x)),x)
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Thanks much and now I have the desired graph looking like your provided image. But when I turn on Trace and vary T, I still get "(NaN,NaN)" at all non-integer T values, unlike your display for T=-5.993 that shows the correct values. (I am new to HP Prime and suspect some trivial configuration setting?)
Edit: No need to reply. It all works if I delete the incorrect version I originally posted.
When I tried with the current version (2.1.14592 (2021 06 09)), I did manage to get a plot to come up after checking (enabling) the Complex setting in Home Settings. ("Allow complex output from real input")
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(I made two copies of the function pair and restricted one to negative T, the other to non-negative T.)